Review: LNA4ALL Antenna Amplifier

Summary: buy one, works as advertised.

What is it?

A small electronic device making radio signals 100-150 times stronger.
Officially called a low-noise amplifier, LNA for short.
Costs 25 euros delivered,
helps you hear and see more targets of interest.

Why?

- To run the RTLstick with less gain,
- To get the maximum from your antennas,
- To add range to your reception ability.

Testing setup

Commercial radio, airplane speech, Weather satellite signals, AIS and airplane position signals are tested. If the LNA delivers as promised on these frequencies, we can assume that it will also perform in the band of your interest.
Antenna is a broadband, commercially-available discone to eliminate antenna errors.
No number-crunching for the review, check the images for exact dB values.
I paid for my LNA, and have no business connection with the manufacturer.

Commercial radio / Upconverter range

Signal strength increase as promised.
This band if of particular interest to those who have an upconverter for shortwave reception.

Airband

Performance slightly better than expected.

Airplane chatter between Plane and Approach/Tower/Ground comes booming in, much better audio, pilot seems talking to you.
Also tested with an Icom IC-R5 handheld receiver, no need to use outside discone as clear reception indoors.

Weather Satellites / NOAA APT reception

Signals are visibly stronger in the waterfall display (quickly connected the LNA during a recent pass), less banded noise in images, same noise floor requires less gain in SDRSharp.

As less gain is required, the stick runs cooler, less internal noise is generated, images are clearer.  

Marine Band / AIS

Increased gain step-by-step until all four vessels in port showed up in Shipplotter, first by MMSI, then by name.

Amplifier connected only half the gain was necessary, performance on par with manufacturer specification.

Airplane position signals / ADSB

Without ampifier, maximum range is 46nm (83km).
With the LNA, maximum range is 52nm (94km).
ADSB Sharp with Tuner AGC on, adsbScope for monitoring, maximum range and aircraft not dropped selected. Monitoring local traffic for few hours and using range rings to establish maximum range, all equipment including antenna height (4 metres or 12 foot) the same during testing.

Ordering and customer service 

The LNA under review is available from this website: LNA For All.
Contact the seller, Adam directly via email for orders: adam9a4qvwashington@yahoo.com/ Remove the capital of the USA to get his real email: name (4letters) and callsign (5 characters).
Seller only charges you when the item arrives, no worries over items getting lost. Payment via Paypal.
Shipping to Ireland took 5 working days, amplifier in a bubble wrap envelope with drawings.
Communication is good, questions via email answered quickly, technical shortcomings revealed openly.
Amplifier worked out of the box.

What you get

A small circuit board, no power supply, no instructions where goes what, no clue how it works except for a diagram showing components and performance.
If you know radio, soldering and electronics, it will make sense, if not, you will turn your 25 euros around, wondering what to do with it and where to start.
The manufacturer states that a "Turn a key solution is delivered" - that's not true. You have to provide power to it.
Note to manufacturers: Please send boards - or make it an option - with a red and black wire for power connector. This nonsense with USB connectors, pins and holes should stop. 

How to make it work

(This is my solution, LNA operational in 10 minutes. Solder if you can or want to)
In the envelope you get a drawing, bottom left of the page shows a picture of what you have, with writing such as GND and + 8-15VDC.
Get a small screw, screw it into the third hole from the left BY HAND.
Too much power = too big screw.
Screw goes through = small screw.
Easy does it, should be just a little bit of resistance as you turn.
That screw is electrical power, plus on your battery.
All the holes in the four corners are negative, minus sign. Use screws, this time falling through the hole, to create four legs, similar to an oil rig.
Create support so the screws to hold the board in place - use a non-conducting material. Ideas: cigarette filter tips (works), scrap plastic from coax cables (might need multiple layers), wall plug fixings (currently in use).
Connect a wire to the screw sticking out from the positive, third hole from top left, by wrapping the wire around it. Write plus sign on it so you know later.
Connect a wire to one of the screws in the corner, this will be negative.

The above method is in use for the last three weeks, the four legs are perfect support for mounting inside a junction box or on a piece of wood.

Power and mobile operation 

Works with 9 to 15 volts.
Officially no over-voltage or wrong polarity protection. My experience is:
It seems indestructible: if the preamp receives 9V to 15V, connected properly, it will operate.
Seems to survive user errors:
- 12V car battery, connected the wrong way: amplifier survives.
- 12V car battery, short-circuited during operation, sparks everywhere: survives.
- Amplifier mounted on top of antenna, no enclosure nor protection, heavy rain: works.
- Rain on amplifier: all works fine.
A great advantage is that either inexpensive 9V batteries can be used for mobile operation, or directly powered by 12V car batteries; no converter needed.
Mount it inside an electrical junction box, power it with a 9V battery and you're ready to go.

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Basically all you need to know to enjoy radio.

Weather Satellites - Software

For about 25 euros you can receive a weather satellite image like this one.

What is this all about?

Around 800 km / 500 miles above your head, weather satellites circle Earth, continuously sending back what they see. You can receive this signal with an RTL stick and create a similar image to the one on the right.
Setting up software is just as important as a good antenna, so this guide details software settings.
Please read Weather Satellites - Antennas for a suitable antenna and construction tips.

Why?

- Real-time observation of weather systems in your area
- Confirmation of other data received, such as WEFAX or NAVTEX signals
- Promotes understanding meteorological phenomenon such as lows and highs in colour
- Receiving an image from a satellite 800 km above your head is fun, educational (Doppler shift, atmospheric propagation...) and lets you view Earth in glorious detail.

What you need

To create an image you need an antenna to receive the signal, software to understand this signal (SDRSharp, free), and imaging software to create an image from this signal (WXtoImg, free).
I assume you have an RTL-SDR stick and installed the software to use it. If not, read the Software Guide on this blog.
The imaging software, WXtoImg can be downloaded from here:

http://www.wxtoimg.com/downloads/wxinst21011.exe

Installation is easy, and once the work flow is understood works very well.

Weather Satellites Background information 

Polar Orbit - Image from NOAA

(no need to read this to get an image, but good to know)

Officially called NOAA 15, 18 and 19, they are truck-sized digital cameras with a radio link to Earth. Imagine your digital camera circling an orange, always over the top and bottom of the orange, the North and South Pole. The orange, Earth, is also spinning, so the camera always sees a different part.
Satellites continuously take a picture of the earth beneath them, sending this signal back to earth in a way similar to TV signals in the 80's.
Because satellites constantly move, you can only see them at a given time.
It's a very simplified explanation, read References at the bottom for more info.

Computer tips and setup

I use a mid-range laptop with Core i3 processor, 8 GB RAM, running Windows 7 64-bit.
Also tested laptops with 1 and 2 GB RAM, was unable to receive images.
Weaker computers can not process the signal and decode said signal at the same time.

Get better images by
- disabling any screen savers (Right click on Desktop, Personalize, bottom right corner)
- disabling programs running in the background - small arrow pointing up next to Speaker icon at the bottom right of your screen shows you what you're running.
- disconnecting wireless mouse and keyboard
- NOT fiddling the touchpad or playing with settings in SDRSharp.
Wireless routers had no influence on received images.
The RTL stick is covered in 5 layers of cut up aluminum cans, connected to the laptop with a 1 metre extension cable.
Antennas are connected with 5 metres of 75-Ohm cable. Tested reception with 17 metres of cable, no difference in received images.
Connectors are BNC, or cables twisted together. Makes no visible difference.
For antennas read the Weather Satellite Antennas section.

SDRSharp Settings

This software uses the signal from the antenna and sends it to the imaging software. You need the following settings:

Mode: WFM. Others will NOT work.
Bandwidth: Write 40000 here, 50000 maximum.
Squelch: Off
Audio Slider: set it to about 70 percent.
Input: Cable Output
Output: Cable Input
Frequency: You can enter it directly or use the buttons on the top of the screen. Only three frequencies are used - you get them from the imaging software.
Satellites are only visible for your radio from a given time, so run SDRSharp 5-10 minutes before the satellite appears. Always double check WFM, 40000, and the Audio settings.
Sample Rate: Selecting 1,024 MSPS in Configuration works better.

Gain settings

(Explaining how to get the best signal-to-noise ratio. Skip if you're familiar with this)

Setting up gain in Configuration is the difference between good and bad images.
Open up Configure (right to Play and left of the numbers) and see the slider - this controls gain of the stick. More gain (slider to the right) - more signal and noise.
Noise is electrical signal you're not interested in - the waves at the bottom of the screen are noise.
Signal is what you want - usually a peak in the top display and coloured dots in the bottom screen.
Now move the slider slowly to the right and watch the waves (noise) at the bottom rise. Just about when they start to rise is a good starting point.
Find a local signal - if you have a big airport nearby google "Airport Name" ATIS - this should give you the airports' info broadcast frequency, tune to it with the big numbers. Hear a voice repeating Landing Runway 30? Good. No airport? Find a local radio, the signal must be continuous.

Note the height difference between the signal (the mountain) and the noise (the waves). Increase gain (move the slider to the right) and find the point where the height of the mountain in relation to the waves are the biggest. Stop there.
Congratulations, you've set up SDRSharp for the maximum signal-to-noise for that frequency.
For weather satellites use this as a starting point, check the image (description on how to below) and increase/decrease according to the image.
Increasing gain to maximum will also increase noise, decreasing the height difference between the mountain and the waves. You do not want that.

WXtoIMG settings

Get the latest satellite information: go to File, then to Update Keplers. This gives you the times of satellites. With WiFi it was automatic for me, if not working, go to Options - Internet Options. Information what the software is doing: Bottom left of screen (above blue Microsoft circle) shows you what's happening.

Satellite Pass List, important is the time and frequency of the satellite. The program gets the Time Zone and Date from Windows Settings.
Selecting a good satellite pass: the MEL in Satellite Pass list shows the maximum height of the satellite for your location. Zero is the horizon, 90 is directly above you - higher the number, more signal, better image.
Location setup: Under Options - Ground Station Location enter your location. Latitude: North is plus, South is Minus. Longitude: East is Plus, West is Minus. Unsure of your location? Google the name of your town with coordinates added after the name of town, e.g. Dallas Coordinates gets you 32.7758° N, 96.7967° W. That will be Lat  32.7758, Long - 96.7967 (West  = minus)
Audio setup: Under Options - Recording Options Select Cable Output, so the imaging software can hear what the radio software is saying.

You're ready to go.

Checklist before receiving your first satellite

Do the startup checks 15 minutes before each satellite. During the satellite pass no Facebook, no movies, or you will get horizontal bands in the picture.
Connect your stick to the laptop. Run SDRSharp with no antenna attached, test local radio stations - if you can hear them, you need to block the signals by adding more layers of metal around the stick.
Connect your antenna, check again local radio stations. You should see peaks, indicating that the antenna is properly connected.
Start WXtoImg, check the next satellite pass time and frequency.
Tune to the given freqency in SDRsharp. Mode WFM, Bandwidth 40000, No Squelch, Audio to almost maximum, Cable output In and Out selected.
Press play in SDRSharp.
Switch to WXtoImg, File (top left), Record (seventh from top), bottom of the screen press Manual test.
Check signal level. Bottom right of the screen, small meter with number in the middle should be green colour, number should be between 50-60.
If yellow, audio is not loud enough - Increase in SDRSharp.
If red, audio is too loud - Decrease in SDRSharp.
All good? Go to File, then press Stop - second from the bottom.
Check complete, peace of mind that software is working properly.

Receiving the image

SDRSharp should be running, check again for WFM, 40000, Audio level and CABLE settings.
Start imaging software, go to File, then record. Second option is Record and Auto Process, Check the square next to Create images.
Press Auto record. WXtoImg waits for a satellite, bottom left of screen tells you the name, time, and frequency.
As soon as the satellite appears on the horizon the bottom of the screen changes, program starts recording and you'll start to see something.
First you'll see only black and white dots, then black and white rows, adding up to something hopefully resembling a satellite image.
Let the software finish, then check your final image.
Final image is always black and white, you can add color with Enhancements - MCIR Map Colour IR.

Problems

Black image only - signal from radio software is not reaching imaging software. Squelch is turned on, or proper CABLE settings are not selected.

White and black dots - something is in the way of the antenna so it can not hear the signal.
- Place the antenna higher up, or move somewhere with a clear view of the horizon.
- If you can not see the picture at all maybe 1) the antenna is not ok 2) not WFM selected 3) wrong frequency.

Small bands or rows in the image

- Antenna hears an other transmitter. Move to an electrically quiet place like a forest park, nature reserve or a field.
- Your computer generates noise. Use ferrite beads on the USB cable for the stick or coil the cable in a small circle.

Image is too white or too dark (usually too dark)
The gain in SDRSharp is too much - decrease it slightly. The small bands at the edge of the screen is a good place to start, ideally you should see different shades of gray.

Image is shifted, lines on the sides not vertical
In WXtoImg, go to Options (fourth from left), then press Resync (sixth from top). One or two lines out of sync might remain, you can't help that.

Tips and tricks

- Print off the satellite pass list in PDF format and keep it on your desktop. Install PDF printer software (doPDF recomended, download from here, opens in new window),then you won't need to open WXtoImg to check the times of the next pass. Saves time for a quick check.
- Check, then double-check settings in both SDRSharp and WXtoImg, because the two programs must work together for best results.
- WFM gives you the best picture.
- 40000 as it is a nice big number and only requires two buttons. I've seen no difference with 45000. It can not be less than 37000.

Noise-free images are a result of:
A good antenna - build a QFH (read Weather Satellite Antennas to find out how)
Clear view of the sky - no trees, buildings between you and the antenna
No electrical noise - cover the stick in metal, move out of the city.
Satellite high on your horizon - choose a satellite from the Satellite Pass list with a MEL as close to 90 as possible. MEL Numbers less than 30 are usually full of banding and noise. Image on top of the page is from a pass with an MEL of 87.
Pre-amplifier - also called a low-noise amplifier, it increases the signal more than a hundred times. The gain in SDRSharp is only needs to go up to 28 db, so less internal noise is generated in the stick. A good one costs 25 euros, currently testing one.

References and Further Reading

Satellite info

NOAA 19 on Wikipedia.
National Oceanic and Atmospheric Administration NOAA 19 Spacecraft Status Summary
A technical description of how the satellite sends the signal to Earth by NOAA.
Satview - lets you track where is your satellite in real time. Combine with SDRSharp to show you signal strength, WXtoImg for the transmitted image, then resize program windows so they fit on the same screen and watch in real time. Image will be probably ruined, but still, great entertainment.

Some historical background, an interesting read, people were already chasing satellites with large handheld antennas in the 70's.

WXtoImg

WXtoImg Installation and Quick Start Guide

Similar guide

RTL-SDR NOAA Guide: http://www.rtl-sdr.com/rtl-sdr-tutorial-receiving-noaa-weather-satellite-images/

If you enjoyed this article, or wish to support this blog, 

... go to Amazon and buy my book.  Tips and tricks in the book will save time and money, reduce frustration with computer settings and help you build the best antenna system from shortwave to microwave. Detailed and illustrated step-by-step descriptions on easy-to-do antennas, from shortwave to microwave.
Basically all you need to know to enjoy radio.

Weather Satellites - Antennas

Summary: two meters of wire and a meter of coax for a good antenna, 5 meters of wire and

a wood frame for an excellent antenna.
Cost is less than 10 euros, construction time is maximum one hour for the example here.
Read on to find out how.

Your antenna choices for Weather Satellites are:

1. Monopole with 4 radials. Construction detailed in the AIS antenna guide, elements are 54.5 cm long. Not discussed here.
2. Turnstile. Four wires plus two coax cables. Portable version discussed here, takes 30 min to build.
2a. Eggbeater - add more wire to the turnstile. Tested, better signal strength. Option if don't want to build a QFH.
3. Double Cross / Lindenblad: Complicated to build, not suitable for marine use.
4. QFH, short for quadrifilar helix. A support with four arms, holding 5 metres of wire. Weather satellites use this type - build this.
5. Yagi-Uda: the TV antenna type found on chimneys, requires manual tracking. Not discussed.

Materials

Wire - the thicker the better. Center conductor from cables work, better results with house grounding wire. I use 3mm (No 6-10 AWG for metric readers) solid copper wire with insulation left on. Some guides use 1/4" or 8mm copper tubing, needs special tools.
Support - your choice. I use wood as it's easy to work with, cheap and readily available.
Connectors - screw terminal blocks are great to hold wires in place.
NOTE: WEAR EYE PROTECTION!
Grounding wire comes as two or three 3mm cables combined in one cable. When uncoiled for measuring / cutting, it can hit you with sufficient force to take your eye out. Pieces being cut also fly to surprising distances.

I've built and tested different versions of the following antennas, best performance with easiest construction is discussed here. Form follows function, so the results might not be aesthetically pleasing, but they work.

Portable Turnstile

Built and tested six different versions, received the image on the right with the version below.
Officially called a crossed dipole, basically four horizontal wires with a phasing harness (more on that later).
Wire lengths are either 1.09m (half-wave) or 54.5 cm (quarter wave). Longer length gave no visible improvement and a pain to mount / carry around.
Wire diameter can be either center of coax cable (1mm) or grounding wire (3mm). Theoretically thicker is better, this is true, thicker cable gave better signal strength.
Phasing harness is coax cable cut to a specific length. Some guides recommend 50 and 75 Ohm cables, tested multiple versions, could not see any difference in received image. If googling turnstile antenna for images, you might notice that sometimes only one cable is used on top of the assembly.
I found that having two 75 Ohm cables, four terminal blocks, 3 mm grounding wire and a wood support is a quick, easy and portable solution.
Wires are removable with a screwdriver, making for a compact and transportable package.

Materials

Wire - Cut four (4) 55 cm wire. Remove the insulation for 5mm on only one end.
Cable - You need two cables of a specific length. The length required depends on the insulation type around the center conductor. Strip away the braid and check the material surrounding the center wire.
If it is plastic, you need 36 and 72 cm long cables.
If it is foam (same material as a coffee cup, soft to the touch) you need 43 and 86 cm long cables.
Leave space on each end of the cable so you'll have enough cable to work with. Separate braid and center wire. Folding the center wire onto itself makes for a better connection at the block.
Screws - self-tapping screws (they make their own hole as you turn them) are great.
Wood / mounting block - mount the components on a piece of wood, or inside an enclosure.
Terminal blocks - one end holds the wire, other end connects the cable. Screw one of the screws fully in. This will be a stop for the radials, e.g. the 54.5 cm wire. Also test that the wire fits into the terminal end tightly.

Assembly

Mount the four terminals at 90 degrees to each other, like North, East, South and West on the compass rose. Leave enough space in the middle for the cables.
Opposing ends of the four terminals are connected, so they form a North-South and East-West pair for each of the coax cables. Push the center of the braid into the hole of the screw connector, and tighten the screw. I find it easier to do the braid first, then the center.
Connect the shorter cable: center to West, braid to East. Insulate braid and center as the other cable might come into contact with it.
Connect the longer cable: center to North, braid to South. By leaving enough center and braid to work with assembly is much easier.
Connect the other end of the shorter and longer cable with the cable going to the RTL stick - connect the three center to center and braid to braid. Insulate braid and center separately.
Locate the four 54.5 cm wires, and one by one push into the terminals, fixing them down with the screw.

Congratulations, now you have a turnstile antenna!

Transform this to an eggbeater antenna:

The eggbeater antenna is an improvement on the turnstile, using two loops, each around 220 cm long, so they form a  71 cm diameter circle. The commercial version is used by radio amateurs to communicate via satellite. If you have enough wire give it a go.
Connect the ends of the 220 cm loops into the terminal connections. That's it, the phasing harness you made will be fine, same principle.
I found that even thought the signal is better, it is too large and does not look nearly as cool as the spiral QFH.
Besides, why not build the antenna type actually used on the satellite itself?

QFH, the Spiral antenna

Built eight versions, easiest to construct with best image quality described here.
The image on the right was made with chopsticks taped to a brush to form the frame, with coax cable for antenna elements. Length and distances are critical, materials are not. 
The antenna is made from a smaller and longer piece of wire, fixed to a frame, connected at the top. Google the term QFH - and a huge number of websites, guides and images come up. Recommended ones are included at the end. However, most guides require the use of power and heating tools and/or soldering.This guide shows you how to build a working version quickly with basic hand tools.

Materials

Frame support: Your choice. I recommend wood, with self-tapping screws only a screwdriver required.
Coax cable: due to the wide variety of cable around, their different properties and the pain of connection on the top and bottom NOT recommended.
1mm wire: the required circular shape is easily lost, signal strength is barely adeguate.
3mm grounding wire: RECOMMENDED, keeps its shape quite well.
Copper rods: you need heating and soldering equipment, pipe cutters etc. Theoretically the thicker the better, comes down to tools and personal choice.
Build one with smaller wire first, then progress to thicker materials.
Connectors, screws: as for the turnstile.

Dimensions

Use the calculator here: John Coppen's Online calculator.
For 3mm grounding wire, use bending Radius: 5mm, Conductor Diameter: 3mm.
Press Calculate - do not press Enter, you'll get an error message.

Note the values for both the small and the larger loop, especially lengths and heights. Adjusting the width at the cross arms can be done later.

Support / Frame

Cut six pieces of wood, 360 mm in length - these will form the cross arms.
Screw the arms together so they are 90 degrees from each other - use other pieces of wood to get 90 degrees.
Cut the middle section to around chest-high - so you can work on the top connections comfortably and the final antenna will be off the ground.
Screw the top arm on the top, measure the larger loop height and screw the bottom arm at that distance from the top.
Screw the middle arm halfway between the top and bottom.

Antenna elements - wires

Cut the required length of wire (WEAR EYE PROTECTION!) plus 5 mm on each end. You'll have two wires, one longer and one shorter. Labeling which is which is a good idea. Mark the midpoint of each wire with tape.
Start with the longer loop - tape the end on the top arm, then make a half turn counterclockwise as viewed from the top. If you think of the arms as directions, start at North, make a turn counter-clockwise (to the left) so the same wire ends up on the bottom arm, facing South.
By this stage the other end of the wire probably destroyed half the room, a helper pays dividends. Hint: involve your significant other or kids.
The midpoint of the wire goes in the center of the bottom arm, tape it securely on both sides.
Run the remaining wire up to the top arm, same thing again, half-turn counterclockwise so the two wires will face each other.
Repeat the same for the smaller wire, so you'll have four wires coming to the center on the four arms.
Measure top and bottom arm distances, remember, top and bottom center must be under each other.
Bend the wires into shape, so when you look down on the antenna wires look like a circle.

Top connections and finishing up.

Coax cable (the one used to get the signal to the RTL stick): a small distance below the top, wrap it around the mast 5-6 times - this will help with electrical noise suppression (coiling excess cable has the same effect),
Separate braid and center on one end - leave sufficient length, 5-6 cm (2") to make connections easier.
The center of the coax connects to one side of the small and big loop, the braid connects to one side of the small and the big loop. When viewed from the top:
Center: connects North and West
Braid: connects to East and South.

Using values from the online calculator, measure top and bottom arm distances, center support - arm distances for both bottom and top. Fix the wire in place with cable ties.

Congratulations, you've just made a QFH antenna!

Antenna placement

- View of the horizon: In a city, as high as possible. Trees and buildings block the signal from the satellite.
- On a yacht, mount the antenna at a convenient location, there's no need for height. It's an interesting question how a sail, especially a wet sail influences reception. Also, place the top electronics in a weatherproof box, and pay special attention to mounting due to windage.
- Away from electrics: try not to have electrical devices nearby.
- Preamplifier: if you use one, mount it as close to the top as possible. Cable from the top picks up electrical noise, so go for the shortest length possible. (Amplifiers in a separate post)



Optional to read: for the turnstile you're making a phasing harness, a quarter-wave and a half-wave for 137.5 Mhz center frequency. Divide 300 with 137.5 to get wavelength 2.18m, half-wave is 1.09m, quarter wave is 54.5cm. If you have foam cable, google the writing on the shield and "velocity factor", such as  "RG 8/U velocity factor".
This gives you a number, in this case 0.78. You need to multiply quarter and half wave values with this to get the required length in centimetres.
In practice a few mm either way will not make a difference.

References, credits and further reading information

QFH from coax cables, an excellent read.
QFH from plastic pipes and copper tubing, one of the better manuals. Have the tools? Build one.
If you wonder if a double cross might be better, read this pdf file.
Eggbeater details and construction here, lots of diagrams.
Browse around on this page, a variation of the eggbeater, called a potato masher. What's this fixation with kitchen utensils?
Commercial eggbeater antenna for USD 221 + shipping at http://www.m2inc.com/index.php?ax=amateur&pg=181

If you enjoyed this article, or wish to support this blog, 

... go to Amazon and buy my book.  Tips and tricks in the book will save time and money, reduce frustration with computer settings and help you build the best antenna system from shortwave to microwave. Detailed and illustrated step-by-step descriptions on easy-to-do antennas, from shortwave to microwave.
Basically all you need to know to enjoy radio.

Software - Beginners Guide

SDRSharp - Tips and Tricks For The Beginner.

What you need to know:

- Make sure you have everything connected
- Top left: Airplanes are AM, Human voice is NFM, Music is WFM
- Top middle numbers: red is up, blue is down, scroll with mouse changes frequency on the number quickly
- Increase power / sensitivity in Configuration (top middle).

SDRSharp will work IF:

- You have Microsoft .NET installed
- You have the necessary drivers (Zadig takes care of that)
- The RTL stick is connected to your computer.

You receive radio signals if you have an antenna connected to the RTL stick.

Please read the Installation Guide,  with instructions you will be up and running in 15 minutes.

Connect the RTL stick to the USB port, then start SDRSharp with the shortcut.
- You have to use the USB port used for installation.
- You have to start SDRSharp as an administrator (see the end of the software installation guide).

Start screen - what's what

Starting from the top left corner:
Play button - starts the sound / runs the software.
RTL-SDR / USB - select this for RTL stick.
Configure - how much signal you want.
Don't touch for now. See at the bottom of this document.
Long Numbers - you set the frequency here.
Radio- Mode settings
NFM is needed for AIS and speech,
AM is for shortwave radio and airplane chat,
WFM is for listening to commercial radio and weather Fax reception.
Don't touch the others. You do not need them at this stage.
Window with red line, surrounded by gray area - the red line is the center of the frequency you adjust with the numbers.
The gray area indicates the amount of signals you receive.
Window below red line - this is called a waterfall, shows you signals over time.

Moving down, next window is:

Audio - AF gain is volume control. Makes the audio louder or quieter.
Output: you want to hear the signal - select Speakers
use signals in another software - select CABLE Input - this sends the signal to other software.

Now press Play in the top left corner.

Congratulations, you started your software defined radio!

Magic awaits :-)

You will get the following screen, see the picture to identify where is what:
(Click on the picture to see it large)

The mountain in the middle is the signal. The height of the mountain is called signal strength, the width of the mountain is called the bandwidth. The better the signal, the higher it is, and the more you can hear it.
The area of the gray is called the bandwidth - width of the mountain. You can change it by going to the edge of the gray and pushing the left button on the mouse, then moving left and right (keep the left mouse button pressed down to move the gray area).
Some signals are only a small peak, some are like Mount Everest.
Remember: the higher the mountain - better the signal.

If you know the area under the gray, you can enter manually in the radio panel.
When you change the width on the right, the numbers change in the left, and the other way around.

Useful numbers: 

People talking (Marine channels, taxi): 12500 (12.5 kHz, k=100)
AIS signal: 25000 ( you see the width when you adjust the gray area)

If you do not know the number, you see the signal, and see how wide it is.
Then you can adjust with mouse left click down until the colours are under the gray area.

Changing frequency

- Go to the long numbers at the top of the screen, so when you move your mouse, the number under the pointer will turn either blue (down) or red (up).
You can click, or use the wheel (the middle stuff between left and right click) to change the frequency you want to hear.
- You may use the direct frequency entry, it is on the left called "Frequency Entry (Plugin)"

Adjusting the power of the stick / adjusting sensitivity

If you can't hear it, you need to make it louder. You can adjust the power of the RTL stick (sensitivity) by going to Configure (top left,  left to the numbers) and moving the slider left and right.
Configuration slider - Move to the right - more signals, more to hear.
If the top of the mountain touches the top of the screen you have too much power, move the slider to the left.

So for now you know what to do:
- Change frequencies
- Experiment with different modes
- Tune across the spectrum.
- Use the sliders on the right hand side of the screen:

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AIS Antenna Shootout

Testing five homemade antennas and a rubber ducky for AIS reception.

What you need to know: monopole with 2 radials is best value / performance.
Read on to find out why.

Introduction

The antenna is the most important part of your receiving system.
To get better performance, you can:
1) increase the height of the antenna, or
2) use a better antenna and / or better equipment.

Equipment being the same and height being the same, you need the best antenna, hence this review of available easy-to-do choices.

1) Increasing antenna height increases range

On top of a mountain you see further away - it is the same with an antenna (called line of sight). That's why your existing VHF aerial is at the top of your mast - it's up high. The way radio waves travel might increase range an extra 10-30 %, but do not depend on it.
Nm is short for 1 nautical mile, equals 1.852 km or 1.15 land mile.
An inch is 2.54 cm. Divide cm by 2.54 to get inches.

Height of antenna above sea level - distance to horizon:
3 metres (fixed to cockpit railing) - 3.3 nautical miles
10 metres (small yacht mast) - 6.1 nautical mile
20 metres - (large yacht mast) - 10 nm
50 metres (large merchant ship) - 13.6 nm
From experience, AIS or VHF signal range is greater due to the fact that the antenna is also on top of the other vessel.

 2) Better antenna and/or equipment

At home or on a yacht, you can only change the antenna location until you reach available maximum, then you must get a better, more efficient antenna and / or more sensitive equipment.
Commercial equipment costs a lot as they are made by people doing radio all their lives, equipment works out of the box and you have less worries.
The choice is yours: pay 300 dollars for an AIS receiver or pay 30 dollars for a solution on your laptop.

AIS vs VHF antenna

If you have a Marine VHF antenna / aerial it will be fine for AIS.
Radio signals come to your antenna in waves, like sea waves rippling in a quiet anchorage. The distance between the top of the waves is called wavelength, and can be calculated by dividing 300 with the frequency in question. Marine band is between 156-162, AIS is around 162, so AIS wavelength is 1.85 metres, Marine VHF is 1.88 metres.
Wavelength is important to us, as most antennas are either Quarter-Wave (0.45m - 0.48m) or Half-Wave (0.9m, 3-foot whip as you know it) or variations, e.g. 5/8th wave, 1.5 wave etc.
For the reasons above, your antenna will work on AIS frequencies.
Antennas work not only at the "designed frequency": the quarter-wave 46 cm monopole, essentially a piece of wire and the worst performing in the test, received Commercial Radio at 96 MHz, Airport information at 121.85 Mhz and Taxi driver chat around 164 MHz.
Don't worry, give it a go, it will work.

Antenna testing setup and materials / cost

Location: top of a mountain, no building/trees in the way of the signal from the harbor, no clear view of the Celtic Sea.
Mid-range laptop, 15 meters of cheapest coax to simulate cable run to cockpit mounting, RTL stick connected via 60 cm (2 foot) USB extension lead. Antennas 3 meters above the ground.
Materials were 3 mm diameter copper wire (ask house grounding wire in Europe or No 10 wire in the USA), radials are 1 mm center conductors from a coax cable.
Material costs: grounding cable at 2-3 euros per meter, coax cable between 1-2 euros per meter.
A working setup, consisting of an RTL stick, 15 meters of cable and a homemade antenna works out to around 30 euros (I assume you have a laptop). A standalone AIS receiver costs around 120-130 euros plus shipping from Ebay.
Get in a "make-do" attitude and use what's available.

Monopole (fancy name for a piece of wire)

A 0.46m long wire (1/4th wavelength) connected to the center of the signal cable. 3 versions tested, 1 mm diameter wire from coax cable center, 3 mm diameter wire from house grounding cable, and wire from an extension power lead.
Electrical noise pickup was the lowest with the 3 mm diameter wire, so used that for more testing.
Furthest AIS target is 2.87 nm away.

Dipole (two wires in opposite direction)

0.46m length of wire connected to the braid of the coax, so they now form a 92 cm (3 foot) antenna.
Range doubled to 7 nm.

Monopole + 2 Radials

The center wire of the coax cable is connected to a 46cm wire, then two more wires are added, each 45 degrees down from horizontal / 45 degrees up from vertical.
Radials are wires connected to the braid. Braid are wires circling the hard center wire, when you cut up a coax cable this is the first you meet below the plastic shell.
The antenna looks like a Mercedes sign, or a peace symbol without the circle. All wires are quarter-wave, 46 cm long. The up part is the center wire, the wires connected to the braid are the two wires going down left and right.
Dramatic improvement over a dipole, signal strength up, noise down, maximum range 21 nautical miles, 100% valid signal ratio. Picked up 3 vessels in port 8.27 nautical miles away (line of sight over the city centre, LOTS of electrical interferece)  and a ship 21 nautical miles away.

Monopole + 4 Radials

Two more pieces of wire added, so four wires stick out 45 degrees from horizontal, each spaced 90 degrees when viewed from the top. Wires point like North, East, South and West when looked from above, with the receiving element at the center of the compass rose.
Maximum range 19 nm, less targets received than monopole + 2 radials.

Coax Collinear (two pieces of coax connected the wrong way)

See detailed construction instructions in the hardware guide.
Gave a maximum range of 16 nautical miles with a container ship passing out at sea, but picked up less targets inside the harbor.
This might be a good backup / secondary antenna as extremely easy to make, can be coiled up for transport.

Rubber Ducky Antenna

Your handheld VHF probably has a similar antenna, this was from a radio scanner. Picked up, then lost Navaids and passing vessels, with 24 percent of signal error not the best here.
Usable if you have to.

Conclusion

Three 46 cm wires arranged as a peace-sign / Mercedes emblem offers the best value for money. Existing antennas, whether a rubber ducky, VHF whip or a scanner antenna will work with strong signals, for example a commercial ship within 2-3 miles.
Larger / more expensive antennas and equipment will increase your reception range - but the question remains: 10-20 times the cost for a slight increase in range?

Read more:

Monopole Antenna Wikipedia at: http://en.wikipedia.org/wiki/Monopole_antenna
Dipole Antenna Wikipedia at: https://en.wikipedia.org/wiki/Dipole_antenna
Line of sight Wikipedia at: http://en.wikipedia.org/wiki/Line-of-sight_propagation
Antenna Comparison Charts - note lengths of antennas: http://vtronix-antennas.com/antennachart.asp

Read even more...

... go to Amazon and buy my book.  Tips and tricks in the book will save time and money, reduce frustration with computer settings and help you build the best antenna system from shortwave to microwave. Detailed and illustrated step-by-step descriptions on easy-to-do antennas, from shortwave to microwave.
Basically all you need to know to enjoy radio.