parnass@ihuxz.ATT.COM (Bob Parnass, AJ9S) (01/18/88)
x Television stations can transmit 2 audio signals simul- taneously. The alternate audio information can be car- ried as the Secondary Audio Program (SAP), on an FM sub- carrier. Area TV stations had not used SAP until December 20, when channel 9 provided bilingual coverage for a Chicago Christmas parade. English was carried on the main chan- nel, and Spanish was transmitted on a 78 KHz FM subcar- rier. One can tune a VLF receiver to 78 KHz FM (or use AM and slope detection), and connect its antenna jack to the earphone jack of the television tuned to the appropriate channel. Instead of using my TV, I just tuned my ICOM R7000 to the 191.775 MHz channel 9 WBFM audio carrier, then connected my ICOM R71A receiver to the R7000's RECord jack. The R71A was set to the NBFM mode at 78 KHz. -- ===-===-===-===-===-===-===-===-===-===-===-===-===-===-===-===-===-===-===-=== Bob Parnass, Bell Telephone Laboratories - ihnp4!ihuxz!parnass - (312)979-5414
kaufman@Shasta.STANFORD.EDU (Marc Kaufman) (01/19/88)
In article <2547@ihuxz.ATT.COM> parnass@ihuxz.ATT.COM (Bob Parnass, AJ9S) writes: > Instead of using my TV, I just tuned my ICOM R7000 to the > 191.775 MHz channel 9 WBFM audio carrier, then connected > my ICOM R71A receiver to the R7000's RECord jack. The > R71A was set to the NBFM mode at 78 KHz. An easier way to do it with that pair, is to take the 10.7 MHz IF from the R7000 and feed it to the converter input of the (in my case IC751). Then tune to 10.778 in NBFM. The rejection of the main channel is not as good, though. Marc Kaufman (kaufman@Shasta.stanford.edu)
Oliver@cup.portal.com (02/09/88)
There is another subcarrier above the SAP called the professional channel....This is used to communicate data and voice to and from field units withen the range of there transmition range. Don't know the frequency right off...but if you want more info mail me and I'll bet fer ya!