[Scan-DC] DCA Tower 134.35 vs. 119.1
Terry Pavlick
TPavlick27 at comcast.net
Mon Jan 25 23:15:01 EST 2021
About the reverse logic
119.100 transmits with lower power since the aircraft are either in the air close to the airport or on the ground at the airport. 134.35 transmits with either normal power or higher power since the helicopters operate at a lower altitude further from the field and may either be blocked from line of sight by buildings, geography or even on the ground out of line of sight with the antenna. Local control needs less coverage since the aircraft are local while helo frequency needs to be heard whether on ground or low altitude.
Terry
Sent from my iPhone
> On Jan 25, 2021, at 16:55, Andrew Clegg <andrew_w_clegg at hotmail.com> wrote:
>
> It's not related to the number of planes or the amount of aviation activity. I'm in Arlington and can copy the tower fine on 119.1. But the interesting aspect is that the tower signal on 134.35 is several dB stronger than the tower on 119.1. And as Dewey noticed (as have I), if you're in the parking lot at Gravelly Point, within line of sight of the tower, the 119.1 signal is surprisingly weak (or at least not nearly as strong as expected), while the 134.35 signal is strong. What I've wondered is whether the 119.1 signal is uptilted a bit (i.e., avoiding radiation from the antenna going downward toward the ground), since that channel is generally communicating with planes in the air; and 134.35 is not uptilted or not uptilted as much, because it's communicating with helicopters that tend to be at lower altitudes than planes. It's just a hunch, probably wrong, but it is interesting that at or near the ground, 134.35 from the tower is stronger than 119.1. I'm not at home at the moment but I can grab some RSSI measurements and audio clips to show the difference between the two signals as observed 5 miles away with an antenna up 220 ft. Definite difference in signal strength.
>
>
> 73,
> W4JE
>
>
>
>
> ________________________________
> From: N4JOG <n4jog at comcast.net>
> Sent: Monday, January 25, 2021 3:40 PM
> To: Andrew Clegg <andrew_w_clegg at hotmail.com>
> Cc: Dewey <dewey3 at gmail.com>; Scan DC <Scan-DC at mailman.qth.net>
> Subject: Re: [Scan-DC] DCA Tower 134.35 vs. 119.1
>
> I live in Woodbridge and hear plenty of traffic on 119.1 and 134.35. 119.1 especially when air traffic is landing to the north. Keep in mind that there are still fewer flights in the air. Things should increase sometime after this pandemic is brought under control. 125.65 is also a busy freq. It gets used by the DOE aircraft when it does its surveys and flies out of Manassas.
>
> Ted Royster
> N4JOG
>
>> On Jan 25, 2021, at 15:17, Andrew Clegg <andrew_w_clegg at hotmail.com> wrote:
>>
>> I have had the same experience. I’ve wondered whether the 119.1 signal is uptilted compared to the helicopter rebroadcast on 134.35.
>>
>>>> On Jan 25, 2021, at 2:12 PM, Dewey <dewey3 at gmail.com> wrote:
>>>
>>> Sometimes, I wonder if there's a propagation issue. I've sat at Gravelly
>>> Point and had problems picking up the tower on 119.1... go figure. I've
>>> already heard 5 transmissions between the tower and planes on 119.1 from my
>>> home since your message about 3 minutes ago. So with that said, 119.1 is
>>> still tower <> planes, but receiving it can be very location dependent, at
>>> least to me.
>>>
>>> Dewey
>>>
>>> -----Original Message-----
>>> From: scan-dc-bounces at mailman.qth.net <scan-dc-bounces at mailman.qth.net> On
>>> Behalf Of Alan Henney
>>> Sent: Monday, January 25, 2021 14:04
>>> To: Scan DC <Scan-DC at mailman.qth.net>
>>> Subject: [Scan-DC] DCA Tower 134.35 vs. 119.1
>>>
>>> I hardly hear much on 119.1 and since 134.35 is helicopter control, what's
>>> left for 119.1?
>>>
>>> Thanks,
>>> Alan
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