I am in the Nashville area and mainly listen to Metropolitan Government Of Nashville & Davidson County (P25) channels. I was having issues where some days I would pick up lots of transmissions (but with lots of interference and errors) and some days would be completely silent. I recently discovered that it has 100% to do with the positioning of my antenna (stock). I have to have it laying down almost horizontally and pointed out the window to pick up signal. Once I figured out the exact positioning I have 5 bars and no interference/errors. Is antenna positioning really that problematic? This is my first venture into the radio scanning world, so forgive my ignorance!
VERY sensitive antenna positioning
- Thread starter jasondcannon
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Also had an interesting issue when it was storming yesterday that transmissions stopped. When the storm passed it went back to normal operation.
ridgescan
Member
I will tell you that the same is true of outdoor antennas at the higher frequencies due to line-of-sight. My discone on the roof will get a given signal in a certain spot up there-if I move the antenna a few feet from there that signal will disappear. So it goes for all the stuff I want to get, so as a result the antenna is positioned at a point on the roof for a compromise amongst most of the stuff I want to receive. Also, I get a better shot at some stuff even by switching a 5' mast to 10'. Touchy.
Its critical for me by inches or less. It could mean you will decode or receive the system or not. I have my telescoping antennas set and can't be moved. I'm under the basement steps. PC and radios...(rec room)...(man cave)... there definitely is a sweet spot on the right side of my desk.
When I ran a feed I have an older PC tower on a dresser in a bedroom upstairs. I ran a 396T on top of the tower. I put a chalk mark around the base of the scanner to insure it was in a sweet spot. I guess size does matter.:lol:
Isn't that the truth!. When the wind blows, the decode rates are all over the place due to trees reflecting the signal as they move, On calm days, not as bad.
That can also be caused by the transmitting antennas moving. While many higher frequency systems use more rigid antennas for that reason, some do not.
I don't know if you are a technical person, but a half wavelength at 860 MHz is about 6.4". If the top of an antenna moves that much, the signal from the top that is 180 degrees out of phase nulls out the signal from the bottom and you end up with no signal. It's more complicated than that, but not much more. Point is that with long flexible antennas the wind does affect the signal strength.
This happens at UHF and even VHF to some degree. That's why I haven't installed flexible antennas for over 20 years for any site equipment.
I don't know if you are a technical person, but a half wavelength at 860 MHz is about 6.4". If the top of an antenna moves that much, the signal from the top that is 180 degrees out of phase nulls out the signal from the bottom and you end up with no signal. It's more complicated than that, but not much more. Point is that with long flexible antennas the wind does affect the signal strength.
This happens at UHF and even VHF to some degree. That's why I haven't installed flexible antennas for over 20 years for any site equipment.
I have to agree with the base antenna movement. I have been told by a reliable professional that the wind will/could/may cause the antennas to swing a bit causing many problems with reception. If that is a known cause then I wonder why they don't put a twenty dollar bracket near the top of the antenna and the other end to the tower. Pretty simple fix. And, I too have noticed, sometimes, that if I lay my scanner almost vertical I too can get much better signal/reception. Very odd.
troymail
Silent Key
We're all looking forward to a future scanner that properly fully receives and decodes simulcast systems. Having said that, some users of actual subscriber radios have occasionally reported their radio not receiving 100% of the time either.
For now, scanner and antenna position plays a big role in better (but not complete) reception. And has been stated, occasional (mostly seasonal) adjustments in position will likely be required.
For now, scanner and antenna position plays a big role in better (but not complete) reception. And has been stated, occasional (mostly seasonal) adjustments in position will likely be required.
jim202
Member
This whole discussion seems to be based on fighting to receive a simulcast system. What does it seems to be an issue going to a directional antenna and pointing it to the nearest tower. This should help null out or reduce the signal from other towers and allow good reception. The down side is now you have a dedicated receiver for just that one system,
If your looking to receive other traffic from other agencies outside your local area. Then use a second scanner on an omni antenna. Use the antenna best suited for the purpose. You can't fight the physics of radio propagation. You can only use it to the best advantage it will provide.
If your looking to receive other traffic from other agencies outside your local area. Then use a second scanner on an omni antenna. Use the antenna best suited for the purpose. You can't fight the physics of radio propagation. You can only use it to the best advantage it will provide.
This is a problem with single site systems also I am 30 air miles from a site (Dyersburg Public Safety) that was designed to cover 20 air miles so when weather changes so does the signal the decode rates go up and down. I am 25 air miles from a TACN site that has 20 air mile range on my pro197 running pro96com I see signal levels from 66% to 100% that very with weather this is using a ST2 at 25 feet to center of the antenna. My BCD536HP decodes both of these systems 95% of the time. At work I have a 48 foot ST2 and a discone side by side the discone works better for the TACN system both are the same height same feedline side mounted on a tower discone east ST2 northwest. The Discone also gets the MOSWIN sites from the Sikeston area 100% as does my ST2 at home.
That's because you're dealing with the laws of physics. When the antenna moves and causes the 180 degree out-of-phase nulling, it affects any receiver. And that is why the theoretical "perfect receiver" will never exist. You can't recover a nulled signal. It violates the laws of physics.
D
darunimal
Guest
As well as turning an antenna can change the height of the perfect sweet spot, doesn't matter if the whips 40inches long, if its turn horizontally to 13 degrees and the total rise is only 6.9 inches then its perfect for 813mhz at half a wavelength. That is why mid and late 90's cell phone (think STAR-TACs) used an antenna longer than necessary but since it would be held at an 115 angle on the left ear (65 on the right) it would have a near perfect length. Now as your pointing suggest you actually have a null spot directly in the top (and bottom) of the antenna, its possible you're nulling out the interence your scanner is picking up that makes it quiet in the first place. Sometimes using ATT and sometimes Squelch help, sometimes Manual p25 threshold settings help too.
I noticed on various handheld and base scanners just rotating the scanner, standing upright, on a table to a different direction can change the antenna strength dramatically, just now they doesn't face me (or even the same direction) but they pick-up the signal alot better
"Who woulda thunk it"
I noticed on various handheld and base scanners just rotating the scanner, standing upright, on a table to a different direction can change the antenna strength dramatically, just now they doesn't face me (or even the same direction) but they pick-up the signal alot better
"Who woulda thunk it"
while new with scanners ... i also have noticed few channels (air-band) will transmit with a small buzz (some days) while some others channels are fine
The squelch may helps in some cases
Regarding the antenna ... again while i am new with scanners ... i had an old dipole designed for the FM band here in Europe 88-108 MHz (75 cm each aluminium)
It has improve the reception of the air-band
With dipoles you can leave it vertical so it picks signals 360 degree
or
placed it horizontal and in this case its becoming directional (stronger reception) in general guide lines
13 euro is the cheapest & most effective antenna & can use it for 360 degree reception or directional
The squelch may helps in some cases
Regarding the antenna ... again while i am new with scanners ... i had an old dipole designed for the FM band here in Europe 88-108 MHz (75 cm each aluminium)
It has improve the reception of the air-band
With dipoles you can leave it vertical so it picks signals 360 degree
or
placed it horizontal and in this case its becoming directional (stronger reception) in general guide lines
13 euro is the cheapest & most effective antenna & can use it for 360 degree reception or directional
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