Radio Data System (RDS) > MRDS1322
19khz Pilot filter options?
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radiowavesokc:
Hi. I have a station that still utilizes an old Orban 8100XT/2 processor. I'd like to utilize a MicroRDS unit for this station if possible. Here's the challenge: How can I extract the 19khz pilot so the MicroRDS can lock onto it? Is there a simple filter for this, or is filtering fairly difficult?
Thanks,
PR
Jan:
If pilot is not accessible anywhere (MPX only), you have 3 options:
* Use PIRA32
* Leave it unsynchronized (suitability depends on application)
* Use the pilot filter below
Pilot filter
Input MPX level at least 1.2 Vpp. Recovered pilot is available at PLT. Signal /SNC goes low if pilot is detected.
Part list:
IC4 – LM567
IC5 – TLC272 or any opamp
L2 – 09P-152J (1.5 mH)
R17 – 2k
R19, R26 – 10k
R15, R18 – 15k
R16, R20, R21 – 33k
R28 – trimmer 5k
C6, C12, C24 – 100n (C)
C8 – 10u (E)
C9 – 100u (E)
C25 – 4n7 (P)
C21 – 3n3 (P)
C22 – 220n (P)
C23, C29 – 1n (C)
C27 – 47n (5%, P)
C28 – 330p (C)
Adjustment:
With no input signal connected, adjust 19 kHz (+/- 100 Hz) on PLT using trimmer R28. Alternatively connect the MPX to input and adjust the R28 to the position where /SNC goes low.
Ross:
Hi Jan,
I was going to make up a couple of these 19Khz Pilot Filters and looking at the Circuit I noticed in your parts list
C29 & C23 are listed as " in (C) " ie No Capacitor Value given.
Any thoughts what these caps should be ?
Thanks,
Ross :)
Jan:
1 nF ceramic type
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