Icom Pcr1000 Wideband Reciever Drm Conversion Manual

							 
 
 
 
 
 
 
  
 
 
 
 
 
 
 
 
Modifications of an Icom PCR1000  
For 
 DRM Reception
  
 
 
 
 
 
Author G Dobson 
Date: 15 February 2003 
  
						

							Introduction 
 
The Icom PCR 1000 is a software-based receiver that is ideally suited to 
conversion for DRM reception with the minimum of modification to the 
existing circuitry. The Icom PCR 1000 has been successfully modified to 
receive DRM signals using the Fraunhofer DRM software distributed via the 
www.drm.org
 website. 
 The modification makes use of the universal downconverter available from 
www.sat-schneider.de
 website. 
When tested using a DRM modulator the receiver yielded results up to 
29dBs SNR. 
 
Modifications 
The receiver has software controlled IF filters capable of passing the widest 
DRM signals (20kHz), ample space for the downconverter board and easy 
connection to the circuit boards without intrusive modifications, for those 
with a fine Soldering Iron and a steady hand! 
 The universal mixer converts the 3
rd IF (450kHz) to 12kHz using a SA612A 
mixer and LC oscillator; there is a crystal oscillator available from Sat- 
Schneider but it is not suitable for this IF. There are only three connections 
to the board: the IF input, which is taken from the output of a buffer amp 
feeding the AM detector, the 12kHz output, which is connected to an unused 
contact on switch S1, finally the DC input, connected to the switched 
13.8Volt input. 
The only other items needed are 20cms of RG178 coaxial cable and a short 
length of insulated wire. 
 
Interconnection 
Using a Dell Latitude C800 laptop with a Maestro sound card fitted: 
connection is between the 3.5mm Stereo microphone socket, and the 3.5mm 
external speaker socket on the Icom PCR1000. In an endeavour to minimise 
changing the Icom the wiring between the units the wiring is not standard, in 
that the wiring from the Icom is connected to the centre element of the plug 
and goes to the tip of the other plug that is fitted into the sound card. 
						

							Setting Up 
The standard DRM signal used for HF broadcasting has a bandwidth of 
10kHz therefore the IF filter is set to 15kHz and AM modulation on the 
receiver PC interface. 
 Note:  the 12kHz output is an inverted spectrum of the original signal 
therefore the DRM software receiver will only decode this if the ‘Inverted 
Spectrum’ is selected in the Setup menu: 
 
To set the 12kHz frequency use a known stable frequency source; a standard 
broadcast will do and tune the carrier to the centre of the DRM display using 
the Ferrite core in the inductor of the downconvertor. 
 
To set the 12kHz level output measure the output using an oscilloscope 
whilst receiving a DRM broadcast, set the output to give 600-700mV P-P 
using the ‘pot’ on the downconvertor board. Optimisation is achieved by 
‘tweaking’ for best SNR. 
 
Results 
Using a DRM Modulator broadcasting a 10kHz DRM signal on a frequency 
of 9780kHz the following results were achieved: 
 
 
Signal level   SNR dBs 
S9 29.2 
S7 28.8 
S5 28 
S3 25 
S1 22 
 
 
Field-test results yielded SNR figures between 18 and 24dBs from the Sines 
(Portugal) transmitter on 15440kHz received in Warwick UK. Reliable 
reception was achieved using the 0.7 metre telescopic antenna included in 
the Icom package. 
						

							Board Layout 
 
 
 
 
 
 
1 
 
 
 
 
 
2 
 
 
3 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
4 
 
 
 
 
 
 
  
						

							Board Layout & Circuit Details 
 
1. 12kHz output connection 
 
                                            
Coaxial cable inner connected here 
                                               Screen unconnected 
                                                     Switch S1 in the speaker position 
 
 
 
 
 
 
 
 
 
 
 
 
2. Power Connection 
Pin 3: switched DC line 
 Connect Here 
 
 
 
 
 
 
 
 
 
 
S1  
						

							Board Layout & Circuit Details 
 
3. 450kHz to 12kHz Downconverter 
 
Board earthed with pins through plated holes, it is not recommended to 
enlarge holes due to proximity of layered track.    
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
4. RF Connection 
  
Coaxial cable inner connected to plated through hole 
Screen unconnected