The short
version: Use a wide-band SDR, HDSDR for surveillance and recording, and SDR
Console for playback. And FMList for loggings!
As a Jaguar
for Perseus user, I am used to being able to see (quite literally!) if there are
potentially interesting signals on the MW band, both live and for the past
minutes/hours/days if I’ve been away for some reason. Continuous or scheduled
IQ recordings then make it possible to «go back in time» and log stations.
This is a massive step forward compared to «linear» DX-ing and makes the DX hobby
a lot more interesting. Why? Because you hear more stations! Of course, you can
record IQ files at random for later analysis, but you must listen through them all to be
sure not to miss anything. You do not have that much time. So, seeing potential
DX is a vital part of the DX hobby in my view.
What
about FM? There is no Jaguar software equivalent for FM. Es and Tropo
conditions are much more random by nature than MW propagation. So, if you want
to log FM stations, you need to be there when it happens, either by sitting in front
of the radio yourself or rely on alerts from fellow DX-ers or FMList.org. Openings
are easy to miss – you may have other things to do – and sometimes openings
close, just to open up again half an hour later. And you were not there were
you?
Enter HDSDR: See the stations
So, to keep
on top of DX events, you need to see the signals. And you need to record them
without knowing if there is anything interesting on the band. And there is a
method to do so which in many ways resembles how Jaguar for Perseus works.
Fellow
DX-er OJ Sagdahl and I learned recently about two documented, but to us
unknown features in HDSDR: The combination of ‘Low Speed Waterfall’, and ‘Save Current RF Waterfall to Image File – Periodically’. Low Speed Waterfall enables
you to slow down the waterfall, thus making it cover a longer time span. The
Save Current Waterfall function will save the RF waterfall as a BMP image at
intervals you set. Waterfall is far better than spectrum to detect signals, so I
suggest you minimize the spectrum display as much as possible. To make the
waterfall even bigger, you can collapse the mode section so that only the waterfall
and spectrum (or what is left of it) are displayed (see image below). This combination enables you to check a day’s DX by using a minute to scan through your image
files and see if anything interesting has happened. Make a note of which times are interesting to check. Then, play back the recordings you made.
If there is nothing of interest in the image files, you can delete the recordings you made (and the image files as well if you want to). This way, you keep hard drive consumption to a minimum.
 |
| HDSDR playing with mode section collapsed |
Since HDSDR
is connected to the SDR you use for scanning the waterfalls, you also need to
use HDSDR to record the IQ files. This is straightforward. HDSDR has a good recording scheduler, it is super-easy to start an IQ (or RF in HDSDR terms) recording on
the fly, and HDSDR lets you organize your IQ files in a logical matter. Such as
one folder for every day. This makes recordings much easier to retrieve. Just
be sure to select “PCM 16” instead of “Auto” for sampling rate, because “Auto”
is 32-bit instead of 16-bit and your recordings will double in size for no
purpose. And speaking of size - individual HDSDR files should be less than 4 GB. I use 3.8 myself.
There is however a better alternative when you want to play back your files.
Enter SDR Console: It’s
playback time
Say you
find half an hour of interest, you have made an IQ recording and you want to
check it. The best option for playback is without a doubt SDR Console. For two
reasons: First, Console has an excellent RDS decoder. Some say it is almost on
par with the standalone RDS Spy. Second, Console playback is file size independent. Console
collects all the files from a recording session to a single playback resource. With
Console’s Analyser, you can jump to any minute in the recording, go back and forward in
predefined time intervals, and it lets you create a playback loop so you can
check a certain time span again and again. And most important, you don’t have
to think about loading another file. An overnight HSDR session with dozens of IQ files is handled as one “file” by Console.
Console
lets you create MP4 video files on the fly, for your personal archive, for
bragging to fellow DX-ers or for reception reports.
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| RDS display (bottom left), playback analyser (top), file info (bottom centre) |
Why use two programs?
Because
HDSDR has properties Console hasn’t, and the other way around.
An added benefit
from using one program to record and another to play back, is that you can
continue to record IQ files while playing back recorded ones.
My own setup
comprises three RSPdx from SDRPlay, connected to one PC each. Each of them
samples 8 MHz to cover the entire FM band. The IQ recordings are routed to an
external high-capacity hard drive connected to each PC. I use Seagate 2.5”,
4-TB drives. HDSDR can handle just about any good-quality SDR available (except
newer RF Space and Winradio SDRs). SDR Console plays back HDSDR files extremely
well.
FM List (fmlist.org)
FMList, together with MWList, DABList and TVList, is the brain child of Günter Lorenz, and is maintained by him and a large group of editors. It's arguably the best combined source for databases and logging stations on the planet. Using the database to log stations is exceptionally simple, and surely accounts for the large number of FM DX-ers, especially in Europe, who use this resource. It's not perfect in every aspect, but nothing else comes close for the FM DX-er.
