[TenTec] DRM on the RX340

Paul Christensen w9ac at arrl.net
Wed Jul 14 07:44:10 EDT 2004


As Carl points out, the DRM transmissions sound extremely good coming from
the RX-340.  Carl's software makes DRM interfacing into the RX-340 a snap.
With one "right click" of the mouse, all RX-340 receive parameters are
optimized for DRM reception.

DRM is not without its faults: it is especially sensitive to co-channel
interference from analog AM transmissions.  For example, on some evenings, I
can record a received signal level of +40 dB/S9 from the Sackville, Canada
DRM facility (9800 kHz), but the SNR may only be 8-10 dB.  After scratching
my head for a while, I realized that a low-level AM station was transmitting
beneath it.  But when the transmissions are open and away from interference,
the streaming is nearly flawless, except during periods of very deep fades,
where the human ear can (under AM) still resolve skywave phase distortion
better than the DRM decoder.    Because the decoder must stay locked to the
DRM coding, any drop-out results in 1-5 seconds of silence until the decoder
can again achieve synchronization.

-Paul, W9AC

----- Original Message ----- 
From: "Carl Moreschi" <n4py at earthlink.net>
To: <tentec at contesting.com>
Sent: Tuesday, July 13, 2004 7:43 PM
Subject: [TenTec] DRM on the RX340


> I finally got around to trying out DRM.  I fired up my RX340 and got the
> freeware program "Dream" installed.  I have been listening to a station
from
> Canada at 9800 kHz for the past several hours.  I am totally blown away by
> the extreme high fidelity of this mode.  I have my software setup so you
can
> right click the "FM" mode button and it automatically sets up all the
> special parameters for the RX340, RX330, or RX331.  This mode is really
fun
> and sounds every bit as good as any hifi FM station I have ever listened
to.
>
> Carl Moreschi N4PY
> Franklinton, NC
>
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