Simple QRP projects, 10m, 6m, WSPR beaconing, LF/MF, sub-9kHz, nanowaves and other random stuff
RogerI think you are right and I am surprised that DRM broadcasting still goes on. Some years back I added a DRM board to be old Trio R1000 and from time to time I tune around the SW bands for DRM. There are quite a few stations still using it including as you say the BBC, Vatican Radio, All India Radio and Voice of Russia. When it works DRM is impressive giving FM-like quality on shortwave. Its downfall however seems to be that firstly you need a very strong signal for it to work, and secondly the manufacturers did not support it. It is not possible and never has been to buy a reasonably priced shortwave radio with DRM onboard. As a new technology for shortwave DRM seems to be dead in the water. The question is why are some broadcasters still using in and who is listening?73 Kevin
I totally agree, and I think the same can be said of the money being spent on DAB and the drive to an unwanted, unasked-for digital switchover. I think it's a situation akin to the promotion of D-Star on the ham bands. The technologists are in charge of the decisions and their belief that the new technology is better is being allowed to overrule the majority user view that we're quite happy with what we have been using for years, thank you.
We yet have a chance to save Band 2 FM.
I do lisen to radio5 on with DAB radio, because the Mediumwave signal is so poor were I live.There is no radio5 service on VHF band2.DAB is not practical in vechicles due to reception blackspots. The major drawback with DAB radio is drop outdue to propagation problems ie. multipath reception dueto the toppgrathy and also aircraft flutter.The sampling rate is quite low, not a problem for speechbut for music quality the sampling rate needs increasing.There is the problem of burbling due to partial dropout.With good old analogue FM you have the capture effectonly the strongest signal will be received.The only way to overcome drop out, would be to installots of local transmitters, too costly.There is a drop in sales with the lisening public losing interest in DAB radio.The D star system is being forced on to Radio Amateurs with analogue repeaters beinig converted to D Star.The local repeated in the Scarborough area has beencnverted to D Star leaving most local amateurs mobileunusable. Some repeaters have been converted to dualoperation. D Star radios are only produced by one manufacturer ie. Icon and they use there own Codec forencoding speech. If yeasu bring out another systemthat's going to cause major non comparability problems.
Sorry about the formating and predictedtext, using an Ipod touch
Why do the DAB broadcasters need band2 when they already have band3.Are the broadcasters moving to band2leaving band3 equipment obslotete?
Hello Roger !DRM is a waist of money, in my opinion. RDPÏ (Portugal) started two years ago to transmit on DRM for one hour on Saturday and Sunday, just for experimental investigations.Also I can say that DAB is dead here in France and they are going to stop it.
If AM shortwave receivers could use updated technology (synchronous, smart DSP detectors and digital filtering) rather than the ubiquitous diode and grotty ceramic filter, AM shortwave could actually sound quite good! The effects of deep-fade causing horrible audio distortions are far better, and with decent DSB IF processing, the full audio spectrum can be decoded.. anyone with an SDR radio can tell you how good it CAN sound. I agree DRM is perhaps not the best solution due to the complete loss of signal during a fade that loses the lock. DREAM takes several seconds to recover which is far more annoying than an AM fade. The DRM signal levels need to be very much greater than AM.
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There is a very mixed review of the new Heathkit kit (the GR-150) on http://www.amateurradio.com / today. Although I admire the attempts to...