[SMCARA] Software Defined Radio

[Rob Renoud]

Dan and everyone,

I have an earlier version of a Softrock receiver that I am currently finishing.  It covers HF and 2 meters.  It is essentially the same circuit as the current Ensemble radio that you have.  Don’t know about the TX side of the radio, but the Ensemble rx with a Tayloe detector is really a nice performer.  You do need to provide band-pass filtering on the input to a SDR receiver as they are particularly vulnerable to strong out of band signals.  My Softrock has a switchable bandpass filter for the HF bands.  Take a good look at the spectrum of the software defined TX as they are often plagued with unwanted spurs.

I am currently working on a project evaluating the various low-cost and professional SDR receivers for 2 meter EME.   I am looking at overall performance of each of the radios as well as their ability to handle noise (one thing SDR radios and software are particularly good at).  The SDR receivers I’m looking at include:  Softrock (Lite + USB Xtall v9 with the si570), FunCube Dongle Pro, FunCube Dongle Pro Plus, SDR-IQ, Flex 5K, and the IQ+ (coming for Christmas!).   I will be using the  software package Linrad (developed, maintained and distributed freely by SM5BSZ) for all the receivers as Linrad has by far the best passive and active noise blankers around.  It is a bit complex, but well worth the time and effort to marster.

I’m hoping to demonstrate the Softrock and FunCube Dongle SDR receivers at the January Show & Tell.  Look forward to comparing notes on our progress.

73,
Rob – K3RWR

Date: Mon, 01 Dec 2014 12:45:45 -0500
From: Daniel Metcalf <kb3uun at gmail.com>
To: "smcara at mailman.qth.net" <smcara at mailman.qth.net>
Subject: [SMCARA] Software Defined Radio
Message-ID: <1417455945.2970.12.camel at ZEUS>
Content-Type: text/plain; charset="UTF-8"

Good Afternoon All,

I have gotten my hands on a kit called the ENSEMBLE TXRX
(http://www.wb5rvz.org/ensemble_rxtx/) which is a 1 watt Software
Defined Radio transceiver that can be purchased here
(http://fivedash.com/index.php?main_page=product_info&cPath=1&products_id=7) for under $100.00. 

It appears that one of the key components of this particular system is
the Silicon Labs si570 programmable oscillator which drives the RX/TX
mixers. This kit is not a beginners kit as the builder has to wind all
of the coils by hand. This could take a little time. 

The question I have is has anyone played with one of these systems
before? If so what are your thoughts about the RX and TX quality?


Dan - KB3UUN