Tag Archives: SDR

Guest Post: Using the HackRF One for DGPS Beacon Reception

Many thanks to SWLing Post contributor, Mario Filippi (N2HUN) for the following guest post:

Receiving with a HackRF One, SDR#, and MultiPSK

by Mario Filippi (N2HUN)

The HackRF One is a Software Defined Radio manufactured by Great Scott Gadgets (www.greatscottgadgets.com) and has been on the market for a few years. Having used an SDR-Dongle for several years I felt it was time to “step up” to this wideband (1 MHz – 6 GHz) receiver to investigate a broader breadth of the radio spectrum, so one was purchased from Sparkfun (www.sparkfun.com).

Recently I performed a rudimentary evaluation of its ability to receive DGPS (Differential Global Positioning System) beacons found in the Longwave band between 285 – 325 KHz; this frequency range is well below the HackRF One’s stated lower receive limit of 1 MHz.

DGPS beacons, when tuned using SSB, emit a distinctive warbling sound, and at this QTH, depending on band conditions and time of year, can be heard as far away as the Midwest. Winter brings the cold weather but also excellent conditions for receiving these beacons, some of which were former marine radiobeacons retrofitted to provide greater DGPS accuracy.

The HackRF One, when used with SDR#, MultiPSK, audio piping software, and a good (43 foot vertical) receiving antenna was able to receive DGPS beacons, and two screen captures are below:

DGPS beacon from Sandy Hook, NJ. SDR# using HackRF One in foreground, MultiPSK software in background with decoded information. Click to enlarge.

DGPS beacon from Moriches, NY. Click to enlarge.

I was very pleased that the HackRF One was able to receive DGPS stations, though tuning them in seemed a bit trickier than with a standard RTL-SDR dongle. Since this time of year is not optimal for monitoring DGPS beacons, as well as the Longwave band in general, it’s reassuring to know that come winter I’ll be able to do some DGPS beacon DX’ing with the HackRF One. However, anyone with a shortwave radio and a good antenna can avail themselves of DGPS beacon hunting, just tune down between 285 – 325 KHz and listen for the distinctive warble.

To decode, look into an excellent program like MultiPSK (http://f6cte.free.fr/index_anglais.htm). 73’s!

Thank you, Mario, for another great post!

When Mario told me he had purchased the $299 HackRF One, I was hoping he would do some guest posts about this SDR–DGPS beacons was use I had never thought of. Looking forward to more of your guest posts, Mario!

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Mike’s Virtual Audio Cable (VAC) promotion

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SWLing Post contributor, Mike Ladd, has been working with vendors to lock in promotional pricing on products and accessories commonly used by SDR enthusiasts. Last week, for example, he shared an excellent promotion for high/low pass filters.

This time, Mike has reached out to the author of Virtual Audio Cable (VAC) who has also kindly offered a discount.

VAC is a fantastic piece of software that allows you to port audio from one application to another on your PC without loss of audio quality. For example, if you’re running an SDR and you want to port its audio to FLDigi (to decode SSTV, RTTY, PSK31, or another digital mode) VAC does this for you.

Mike’s discount allows you to purchase a self-support copy of VAC for $21.42 US (a $3.78 discount).

To get the promo price, you’ll need to use this link which has the embedded coupon code, then simply make the selections as shown below:

Click here to purchase VAC with promotional pricing.

Thanks again, Mike, for sharing discounts with the SWLing and ham radio communities!

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Mike’s low and high pass filter deals

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SWLing Post contributor, Mike Ladd, is an avid SDR enthusiast and an administrator of the SDRplay Facebook group. Mike contacted me about special pricing he has arranged for low and high pass filters through Rescue Electronics. Mike explains:

These filters retail for $70.00 each. I spoke to the builder. I told him who I was and what I do and got him to make a deal for anyone in the United States with these filters and a direct link to his site. I make zero dollars on this. I always try to give back to the hobby and the community any way possible.

You have 3 choices: a high pass filter, a low pass filter, or a combo package.

These are hand built one at a time by Paul W1VLF with your choice of SO-239 or BNC connections. Full details are below:

High pass filter $55 shipped anywhere in the USA

This filter will begin attacking the AM band at 1770 Khz and increase attenuation as frequency decreases.

You can see this in the screen capture of the swept filter below.

160 Meters and above is virtually left untouched, but below that is where the attenuation takes place.

The filter has attenuated 60 db by 960 KHz.

The AM band has some very large signals that can mix in the front end of your. A lot of these spurious frequencies can land in 160 meter band or above.

For instance, I have a big signal at 1080 Khz and another at 770 Khz, add these 2 together and you get a spur that falls at 1850 Khz

Picture this happening at multiple frequencies with multiple mixes and you have a raised noise floor in the 160 Meter band.

The filter is built into a 2″ x 4″ 1.25″ 1/8″ wall aluminum enclosure for excellent RF shielding

Low pass filter $55 shipped anywhere in the USA

The AM-2 filter has a cutoff at 520 KHz.

Then, and without a lot of fanfare it begins the attack on the MW band.

Purchase this filter if you are into NDB, DX’ing, Maritime Mobile, Navetex, FCC Part 5 600 Meter band.

Each filter is handmade and swept in my lab.

The AM -2 Low pass is equipped with BNC connectors.

The filter begins to roll off at 520 Khz and gives an ultimate rejection of around 80 Db.

The filter is built into a 2″ x 4″ 1.25″ 1/8″ wall aluminum enclosure for excellent RF shielding

Combo deal for both $100 shipped anywhere in the USA

Click here to view/purchase via Mike Ladd’s promotional page at Rescue Electronics.

Many thanks for sharing this Mike! During my presentation at the Winter SWL Fest last week, I spoke about the need for high/low pass filters for listeners who live in the presence of strong broadcasters and interference. Many of the inexpensive SDRs on the market do not have built-in filters and preselectors thus can overload under these conditions.

While filters can be homebrewed or built from kits, these filters seem to be a good deal for a quality shielded and tested product. Thanks for arranging this, Mike!

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SDRplay RSP update includes broadcast ID

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The SDRplay RSP software defined radio

Many thanks to Jon Hudson at SDRplay who shares the following news:

The latest EXTIO control file (Version 3.8.1) has a very cool new feature for shortwave listeners interested in hunting HF DX stations.

Using the world-wide station list mintained by http://www.eibispace.de/ you can see the name of stations appear in a pop-up window as you select a particular broadcast signal. The details are in the updated EXTIO user guide selectable from the Platforms section or by clicking here.

There’s a video demo here:

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A simple homebrew high pass filter

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Many thanks to Jon Hudson, of SDRplay, who posted the image above along with the following note on Facebook:

David, WA7JHZ has designed and assembled this neat 2.6 MHz high-pass filter (HPF) for use with SDRs. He says that this simple input band-pass filter (BPF) might be of interest to anyone suffering from strong AM broadcast stations that are causing overloads…..David suffers from three nearby AM radio broadcast stations that overload the front ends of several of his receivers, including the SDRplay RSP and this is an ideal, low cost solution. He built this circuit from junk parts and commented that Amidon T44-2 iron powder cores would have made a better design, but that he decided to keep costs down with this design.

This design is simple enough for almost anyone to build and could help your receiver’s front end from overloading. Many thanks to David for the design/schematic and to Jon for sharing!

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Check out the new web-based KiwiSDR in New Zealand

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Many thanks to SWLing Post contributor, Andrea Borgnino, who shares a link to a new web SDR in New Zealand: The KiwiSDR installation.

Andrea posted the following on Twitter:

The new KiwiSDR is fantastic !! Best web-receiver ever !!! https://t.co/YiIEUE3CIe @SWLingDotCom @LondonShortwave pic.twitter.com/d3i9UVynt7

— Andrea Borgnino IW0HK (@aborgnino) February 9, 2016

I agree with Andrea: this WebSDR has an amazing display and user interface. It even includes both a spectrum and full-color waterfall.

I’ve enjoyed tuning around the mediumwave band in New Zealand this morning. My Internet connection is terribly slow (and unreliable) but I was still able to view the full display while streaming audio with only a few hiccups. With a moderately robust Internet connection, I believe you’ll be pleased with the KiwiSDR.

Click here to visit the KiwiSDR online.

Many thanks, Andrea, for the tip!

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Brilliant Article on RTL-SDR Dongle Uses

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Frequent contributor Mario Filippi N2HUN has written a brilliant piece for the latest edition of The Spectrum Monitor entitled RTL-SDR: Your Eye To The Wireless World, February 2016. Here is a brief synopsis:

RTL-SDR Dongle: Your Eye to the Wireless World

By Mario Filippi N2HUN

The RTL-SDR dongle has garnered much popularity over the last several years as an inexpensive and effective broadband receiver for the radio enthusiast. Now Mario shows us how the RTL-SDR can be pressed into serving in other ways: as a rudimentary piece of test equipment to explore those countless wireless devices that power our world and make life convenient. You can use it when restoring vintage radios, doing frequency analysis, antenna analysis and a host of troubleshooting activities you may never have thought of.

I highly recommend buying at least the current issue ($3.00 / PDF Download – what a steal!) or better yet, subscribing for a whole year. Every issue gives far more value than the cost ($2.00/issue at the current subscription rate).

Mario’s article explores things I never would have thought of, and he explains how he uses these inexpensive dongles in place of much more expensive equipment. It is truly amazing what these little wonders can do, and Mario just keeps pushing back the envelope of what is possible.

Thanks Mario for a truly inspiring article – yet again you have given us even more rabbit trails to explore!

Robert Gulley, AK3Q, is the author of this post and a regular contributor to the SWLing Post. Robert also blogs at All Things Radio.

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