Air Traffic, ILS & Navigation Aids

[oldendays]

I'm not quite line of sight for the tower aerials but I'm only about a mile away.

 

[oldendays]

Tels Department is running TX tests on the VHF frequencies this morning. Radar and Radar 2 are much the same as ever but Tower not nearly as good - probably 5/7 bars.

 

[lbaspotter]

I see this evenings Ryanair flight RYR157 to Dublin operated by Boeing 737-800, EI-EVJ has gone straight out departure routeing over towards Blackpool/Fleetwood, then out over Irish Sea. I've not seen them go that kind of direct routing in a very long time!

View attachment 21264

 

[lbaspotter]

And now the Aer Lingus Regional flight "STK8WP" to Belfast City operated by ATR72-600, EI-FMJ has took a straight out departure routing direct to north of the Isle of Man.

View attachment 21266

 

[oldendays]

Strong but distorted transmissions from our Radar Controller this afternoon. I fear he is either speaking too loud or his headset microphone is too close to his face.

It's The Jocks and The Geordies in ATC today (apologies if our friend in Radar isn't from Tyneside)!

 

[quik123]

Or it could be something at your end! How do you measure 'strong', are you tuned to the correct frequency, do you have the correct filter settings on you receiver. I'd have thought if the transmission was genuinely distorted then aircraft would say something.

 

[oldendays]

Distorted audio is what I detected, as if the microphone was defective. The signal itself was strong - five out of five bars and squelch fully clockwise. But it would have been 'readability 4 - slightly distorted'. The Tower controller was clear as a bell - no issues. However, I take your point about frequency. I'm tuned to 134.575 - is that still the actual frequency or is it an 8.33khz frequency ? I couldn't answer your filter question - I don't know what Icom specified on their receivers.

 

[quik123]

Correct frequency but it is an 8.3kHz channel, you might be set to 25kHz which could end up sounding distorted. He has got quite a deep voice so it might just be him!

 

[oldendays]

I listen most days (provided the place is open) so I should be able to notice any differences, plus or minus. It'll be interesting to see if the new Frequentis system has any noticeable effect.

 

[quik123]

When does it change to the new system

 

[oldendays]

Pass. It's certainly installed but I don't know if it's been commissioned yet.

 

[quik123]

I wouldn't think you'll hear any difference. The transmitters and receivers won't be changing

 

[Dave 1959]

Distorted audio is what I detected, as if the microphone was defective. The signal itself was strong - five out of five bars and squelch fully clockwise. But it would have been 'readability 4 - slightly distorted'. The Tower controller was clear as a bell - no issues. However, I take your point about frequency. I'm tuned to 134.575 - is that still the actual frequency or is it an 8.33khz frequency ? I couldn't answer your filter question - I don't know what Icom specified on their receivers.

Strictly speaking the frequency is 134.580 but for straightforward listening it shouldn't matter(just as Tower is 120.305 but sounds just the same on 120.3)I have had similar issues (with various different radios)since the change to 134.575 years ago,it seems to vary depending on the actual controller and their headset---even the weather of course!Out of interest I have never had any problems with 120.3 either ,maybe 2 or 3 bars on 134.575 then a straight 5 on Tower.

 

[quik123]

Not quite true, the channel name is indeed 134.580 but it is still transmitted on a frequency of 134.575 but within a channel plan that uses 8.3kHz spacing.

 

[quik123]

Also worth noting that the aerials you might be using are probably set to the centre of the airband ie near 120.3 whereas 134.575 is very near the end of the airband where your aerial is likely to be inefficient

 

[oldendays]

I usually find a stronger signal on Tower than Radar, even though the transmitter is set at a lower power. Something to do with Designated Operational Coverage. I put this down to my loft aerial being a more resonant length for receiving frequencies around 120 mhz than 134 mhz, plus not quite being line of sight. However, today's issue wasn't signal strength; Tower and Radar were equally good and the high pressure probably helped. It was the distorted audio which caught my ear.

Cross-posted with quik re aerial resonance!

 

[Dave 1959]

Also worth noting that the aerials you might be using are probably set to the centre of the airband ie near 120.3 whereas 134.575 is very near the end of the airband where your aerial is likely to be inefficient

I see where you are coming from on that but I don't recall any particular difficulties when 133.125 was in use(not even from "Our friends in Brussels " who eventually forced the change to 134.575).

 

[Aviador]

Not a technical question by any stretch, but why do radio frequencies change so frequently?

 

[quik123]

I see where you are coming from on that but I don't recall any particular difficulties when 133.125 was in use(not even from "Our friends in Brussels " who eventually forced the change to 134.575

just the luck of the draw! there are many things that can affect aerial performance

 

[oldendays]

Not a technical question by any stretch, but why do radio frequencies change so frequently?

You'd need to ask an OFCOM or CAA staffer about that. I expect it's a complex issue that concerns the VHF radio spectrum as a whole, not just the airband, and involves neighbouring states too. 123.75 and 121.05 were virtually LBA property until they got swiped!