493.2250MHz church? wonna be DJ? london MW7 Area

[francisuk22]

Anyone else around the area hear this and what is it as i can hear church voices and music?

is on 493.2250MHz

[DONNY1]

Hi there what your hearing on the frequencie is uk tv channels <anolog>.
thats the sound channel 23, vision is 487.25. hope helps Don.

[normal]

Yes, until April the 18th 439.250MHz WFM is the ITV1 analog sound from crystal palace.
439.225 will also work because it's wide FM but is slightly off.

It will sound nasty of you have a basic scanner that just does narrow FM.

It will go off air when the digital switchover happens.

Crystal palace TV analog sound frequencies
bbc1 517.250
bbc2 573.250
itv 493.250
c4 549.250
ch5 605.25

[RogerD]

re-jigging the quote.....

439.250MHz WFM is analog TV sound. 439.225 will also work because it's wide FM but is slightly off.

Maybe, maybe not.

The analogue TV network was engineered with offsets to make co-channel interference (during tropo lifts) slightly less objectionable.

To the scanner owner it may appear to be -25kHz or +25kHz from the nominal xxx.250MHz frequency (both vision and sound carriers) when tuning in NFM (or even SSB) mode during silent moments, but in actual fact that '25' is related mathematically to the line frequency and happens to work out at 24.9-something kHz, which is close enough to 25

The French system had, similarly, very close to +/- 37.5kHz offsets on many transmitters.

The offsets weren't always the same on any given TX site, some of the 4 channels may have been + offset (xxx.275), some - (xxx.225), some not at all. Another little bit of technical trivia to be lost to the dustbin of history!

[normal]

Interesting, looks like I was wrong about the exact frequency.

I had a go at the zero-beat method of finding carrier frequencies.

With my receiver on LSB I get a carrier whistle that changes pitch as I tune past radio 2. It is zero-beat at 89.201MHz
I trust the BBC to be spot on 89.200 so this receiver is slightly off.

Channel 1 on a PMR446 radio zero-beats at 446.004 LSB and the carrier whistle shifts as the battery voltage drops. With CTCSS on I get a raspy buzz instead of a whistle.

I just can't get a zero beat on the TV audio carriers. Instead of anything like a whisle that goes up and down in pitch as I tune past it I get a load of noise that drops off in strength over about 15Khz up and down.

Going by the signal strength on LSB I need to correct my list to
BBC1 517.275
BBC2 573.250
ITV 493.225
C4 549.225
C5 605.275

+/-5KHz certainty!