[IRCA] accurian receiver review - part 4 of 4

["Bob Foxworth" <rfoxwor1@xxxxxxxxxxxxxxx>]

Review of Radio Shack Accurian 12-1686 HD receiver
by Bob Foxworth    - in 4 parts

begin part 4 of 4

The receiver also delays anything it handles (analog
or digital, AM or FM) by about 100 ms behind the
signal as heard on an ordinary receiver. If a
previously heard -2 is still cached in the receiver,
the HD unlocks, and the -2 is tuned, silence results.
There were a couple of episodes where the tuning was
changed from a HD to a non-HD and a couple more
buttons had to be pressed to get the sound back.

Aux In. The fifth input option (2 AM, 2 FM and Aux)
lets you feed the output of another sound device
into the set. This is very useful to me. I have
several small digital recorders and can feed the
headset output through the set, with good results.
Take care to not overdrive the input, but a decent
headset level from the recorder should be optimum.

Insides. Here is a posting from the Broadcast list
digest which is quite interesting. As I may yet
return the set, I am not about to open it up.

---------------------
Message: 20
Date: Sat, 2 Dec 2006 19:41:19 -0600
From: "stanleybadams" <stanleybadams@xxxxxxxxx>
Subject: [BC] Accurian Insides
To: <broadcast@xxxxxxxxxxxxxx>
Message-ID: <001701c7167c$225c0440$6001a8c0@stan>
Content-Type: text/plain; charset="us-ascii"

I was tooling around the internet looking for
reviews and information on the Accurian, as I
received mine this week but have not turned it
on yet. Here is what someone posted on a web site
(www.avs.forum.com)  by the name of Eric.  So I
am giving credit where credit is due 

I finally had the courage to open up the radio
and look inside (Hint: some screws are hidden
under the speaker grilles).

There is a Samsung module that plugs into a PCB
named "Table-Top Version 2.2". The Main PCB contains
the Power Supply, Amplifier, and connectors for
the display, speakers, keypad, etc. The Samsung
HDRMDVM0101 module contains the heart of the radio.
The module has a 20 pin and a 50 pin connector to
interface to the Main PCB. The module also has a
JTAG connector for the ATMEL Processor.

ICs on the module include:
ATMEL Mega128L Low Power AVR RISC Processor with
128K Flash
TI TMS320DRI350AZTS5 DSP for HD Radio Baseband
and Analog Decoding
TI DRI8201 Intergrated AFE
Spansion S29GL032M90TFIR4 3.3V 32Mb Flash x8/x16
Bottom Boot Sector
ESMT M12L128324A 3.3V 4MBx32 SDRam
1803A 24bit 96K Stereo Audio ADC
1782 24bit 96K Stereo Audio DAC
LM833 Dual Op Amp

This is a Software Defined Radio where the AM or
FM signal is converted to a 10.7 MHz IF and then
digitized. The digitized IF gets downconverted
and fed to the DSP where either AM, FM or HD
signals are decoded and sent to the Stereo Audio
DAC. It appears even the Aux Input is digitized.

Several companies offer modules based on the HD
reference design so I would not be surprised if
most HD radios use the same scheme. Plug a module
into a I/O board and put a custom user interface/
configuration in flash.

Obviously, the speakers can be replaced or the
audio fed into a stereo system, but as you see
they are modules such as this Samsung, or what
TI or others would build.  It is a single unit
radio that has the real guts in the decoders, not
in the RF section.  Somebody ought to build a
good American made copy of this thing, don't
you think?

Stanley Adams
Memphis

------------------------

This tends to confirm my own thoughts about the RF
behavior. PS a JTAG is a test point to allow
diagnostic and interfacing on a otherwise self-
contained module.

end of review.  20061203. by Bob Foxworth



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