User Manual

PROGRAMMING
3-7
June 1997
Part No. 001-3412-002
IMPORTANT
If the receiver is to be operated at 510-512 MHz (-810),
a spurious condition may occur to degrade the receiver
sensitivity 2 to 3 dB. If this degradation is unaccept-
able, the synthesizer can be reprogrammed to a com-
parison frequency (FCM) of 31.25 kHz (so that a
multiple of this would not be 52.95 MHz) and a modu-
lus (FMOD) of 5 with a reference divide (NR) of 560.
These parameters place the spurious at harmonics of
31.25 kHz (instead of 50 kHz) outside the passband of
the IF filters where the sensitivity is not degraded.
3.5 RADIO DIAGNOSTICS
The diagnostic features allow the user to program
a Digital-To-Analog Converter (DAC) to adjust RF
output power and modulation flatness without remov-
ing the radio from the enclosure. Bit "ao" can be set
to provide an analog voltage representative of the for-
ward and reverse RF power at the radio interface con-
nector J201, pin 14.
This feature can be used to monitor the condition
of the transceiver and antenna/feedline. Figure 3-8 is
a diagram of the Diagnostic Serial Data Stream with
definitions of the bits. It is 19-bits long, the front
(MSBs) can be padded with "Don’t Cares" (XXs) to
get to 24 bits.
Clock (max.) 1 MHz
Diag Enable (min) 250 ns (min)
XX Don’t Care
DAC Bits:
A1 - A0 = DAC Output Select
00=Power Set (Data=0xFF for now,
RNG=1)
01=Mod Adj (Data=0xFF for now,
RNG=1)
11=DAC Control Select (Data=0xFF for DAC Con-
trol)
RNG = Range Select (max. output) (Ref = 5.5V÷2)
0 = 1 x Ref
1 = 2 x Ref
D7 - D0 = D/A Data
0x00 = 0.0V
0xFF = 1 x Ref (RNG=0)
0xFF = approx. 2 x Ref (RNG=1)
Shift Register Bits:
a0 = Diagnostic Select to J201, pin 14 (Analog Voltage)
0 = Forward Power
1 = Reverse Power
Figure 3-8 DIAGNOSTIC SERIAL DATA STREAM
XXXX
XX
XXXX A1 A0 Rng D7 D6 D5 D4 D3 D2 D1 D0
XXXX
XX
XXXX
XXXX ao
LSB (00)
MSB (23)
Data
Clock
Diag En