Software Defined Radio (SDR)
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On this page you will find my review and experience with software defined radios.
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For several years now, I have been wanting to experiment with
Software Defined Radio (SDR).
SDRs have been in development and in service since the 1980s in military communication applications. One could go as far as to argue that the Rockwell Collins HF-2050 receiver, produced for the Canadian Military, was one of the first receivers in this category as it was the first receiver to employ digital signal processing (DSP).
In the early 1990's I had the opportunity to work with a Watkins-Johnson HF-1000. The receiver was somewhat of a disappointment. The HF-1000s performance and features were good but less then a month into service I found myself having to put the unit on the bench and realign the internal frequency standard (TCXO). Once the TCXO was realigned the receiver was back on frequency.
Until recently, most commercial and hobby SDRs worthy of providing solid performance coupled with flexibility have been reasonably expensive. A little over a year ago, a long time friend of mine told me that he had purchased an SDRplay RSP2 as a travel companion receiver. After much procrastination, I decided that it was finally time to jump in and experiment with this new technology. I was sceptical of the performance an SDR would deliver. I live less than 10 km from a major downtown metropolitan area. Historically, any general/average quality broadband receiver that I have owned have all suffered from intermod and IF front-end overload. In August of 2018 I visited my local Amateur Radio shop and invested in my first SDR --- an SDRplay RSPduo.
Having served alongside high-grade commercial and military radios for over 30 years, thus far, the only word that expresses my satisfaction with the SDRplay SDR is WOW! This "little black box" is amazing. For people who know me well, at one time, I used to maintain a fairly impressive collection of high-end commercial and military grade receivers and transceiver. My collection used to span a wide range --- Eddystone, Harris, Icom, Racal, Rockwell Collins, Rohde & Schwarz and Watkins-Johnson just to name a few. Over the past few years I have been pruning my collection down some what to something more reasonable --- from 4+ racks of equipment down to a little over 2 racks and a few shelves --- keeping only a few prize units in active service.
Let the games begin. I am primarily a VLF/LF/HF band user. For my first test, I put my new RSPduo head-to-head with my Harris RF-590 and Rockwell Collins HF-2050. Well, I have to say, the RSPduo is a pretty good contender against these $15,000.00+ receivers. So far, I am impressed.
For my second test, I decided to put the RSPduo up against my ICOM IC-R8500 in the LOS SATCOM band. Thus far, other than my LST-5 and AN/URC-111, the only other receiver that has been able to intercept the Brazilian pirates on LOS SATCOM has been the ICOM. Now I am really impressed. The RSPduo is intercepting LOS SATCOM.
Hummm, so, what about data you say? With the help of VB-Audio's VB-Cable, routing the audio from the SDRuno's application to a software decoder was a breeze. Test number 3 --- I tuned the RSPduo over to an HFDL frequency and within seconds I was decoding aircraft and ground transmissions.
Brazilian radio pirates on 255.550 MHz
|Let's find something a little more challenging. I tuned over to time and frequency station CHU and after a little over 60 seconds I was decoding valid time code. This all software configuration, SDR + decoders, operated from a single desktop is far more convenient then my traditional analog cables from receiver balanced audio outputs to either my external modems, demodulators or computer sound card. Another win-win for the SDR.
Above: HFDL data decoding
Top right: Time and frequency station CHU at 3330 kHz
Bellow right: CHU time code decoding
Receiver: SDRplay model RSPduo
HF antenna: Barker & Williamson model BWD-90
LOS SATCOM antenna: Dorne & Margolin model DMC-120
ADS-B antenna: home built 136 mm vertical dipole (RG-58 coax)
About the author.
Richard Lacroix has been a radio hobbyist since the mid 1970s and has been professionally active in both the commercial and military communication field since the mid 1980s.
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Information & Security Disclaimer
First published: September 08, 2018
Revised: September 09, 2018
(C) 2018-2024, Richard Lacroix. All rights reserved.