Friday, January 25, 2013

Programming WiNRADiO RBASIC

RBASIC (Radio BASIC) is a plug-in for WiNRADiO SDRs.  It implements a small version of the old BASIC programming language, with a number of high-level commands that hook directly into real-time receiver control.

Radio BASIC does not completely resolve the issue of software availability vs the Perseus, but it's a start.  It's a little language, thank goodness.  It is completely procedural.  Like people, it starts at the beginning of a task, does things, and finishes when there's nothing left to do.

Its rudimentary instruction and function sets can be mastered in a day's time by anyone who ever programmed in BASIC.  Those who learned to hate this language, myself included, will be pleased to know that it has no line numbers  at all, anywhere, ever. 

The first program I wrote was a hack of one available on the Radio BASIC home page. The result was a perfectly decent scanner for the low-VHF repeater channels used by the California Highway Patrol.  (The G33DDR goes to 50 MHz.)

The radio functions make this a snap.  Set the squelch, read its state, loop through frequencies, then pause if it's open.

Now, I need another CHP scanner like a fish needs a bicycle, but hey, it works.  It kept up with the general mass chaos of a rainy day on L.A. freeways as well as anything else would have, in this non-demanding application.

What I really needed was an ALE scanner for the WiNRADiO.  Work continues on one.  I've got it so it will read in frequencies from a text file (QRG.TXT), and scan them.  It does not use the squelch.  Obviously, the resulting audio has to be decoded by another program, in this case MultiPSK.  The "would be nice" list includes better checking that the signal is indeed ALE,  and a way to manually pause the scan.

Ahhh, so little time.

Monday, January 21, 2013

Verified HM01 Schedule

HM01 stands for Hybrid Mode number 1. It's the first "numbers" broadcast known that uses both AM voice and digital file transfer modes close together in the same transmission.  Like most strange things nowadays, it comes from Cuba.

The Spanish language "female" voice uses the same digital samples as the existing voice schedule (V02a), which is still on air.  The digital uses the same differential phase shift keying mode (called RDFT) as the earlier SK01, which was so called because an early version used a type of binary phase shift keying called PSK31.

RDFT (Redundant Digital File Transfer) is a very old mode by digital radio standards, having been developed by hams sometime around 2001. It's no longer used much, if at all, except by HM01 and SK01. The other noteworthy feature of these transmissions is that the RDFT is indeed sent in plain amplitude modulation (AM) mode, with two sidebands. These, of course, are identical, except in polarization.

ENIGMA 2000, the people who maintain the Control List of these designators, already has a preliminary schedule for HM01. This editor has been checking its times and frequencies, and the schedule presented here is only what has been heard at this QTH in California.  Times are UTC, frequencies are kHz.

0500: 5855 has been heard Sunday and Monday, and may be a daily sked. 6165 was heard one Sunday.

0600: 10345 weekdays except (maybe) Thursday. 5800 Saturday, 6165 or 10345 Sunday.

0700: 9330 MWF and Sun. An unknown frequency in the 13 MHz range Saturday.

(Other skeds have been logged by others at 0800, 0900, and 1000 UTC. These have not been verified here.)

2100: 11635 MW and Sun. 16180 TThSat. Friday still not found.

2200: 10715 (MWFSun) alternates with 17480 (TThSat).

2300: 11530 (MWFSun) alternates with 17540 (TTHSat).

A lot more details about this weird new mode appear in the Monitoring Times Utility World column.