How Far Can I Scan locally?

[platinumrx8]

I have a Pro-528 and mainly scan the 800 mhz for the po-po and EMS traffic which is based on a trunking system.

But I was wondering what my range is for signals that are local and is there anyway I can boost this range somehow..

 

[gmclam]

Improving reception

It depends on oh so many things, like:
- The type and location of the antenna you are using
- The frequency you are trying to receive
- The terrain in your surrounding area
- The power and antenna height of who you are trying to receive
- The weather/atmospheric conditions
- Your receiver

I can only receive 800 MHz signals from about 60 miles away, and that is under the best of conditions. In any trunking system, I'll receive most of the channels just fine, but there will be 1 or 2 frequencies that are far more scratchy than the others.

The things I did to improve reception; an outdoor antenna, low-loss coax kept to a minimum length, filter out unwanted signals before they reach the scanner (AM, FM broadcasts).

 

[muhockey86]

What kind of antenna set up are you using to get a range of 60 miles on a TRS? I'm about 15 miles south of St. Louis and cannot receive their TRS. This is using a pro-94 and the 800 mhz antenna from RadioShack. I'm trying to see what I can do to improve reception without a tower going up in the back yard.

 

[N4DES]

and a lot has to do with the system that you are listening to. For example is it:

wide area simulcasted,
single site low altitude,
NPSPAC with defined coverage contours?

These items will also affect your ability to receive them that you have no control over.

 

[gmclam]

What kind of antenna set up are you using to get a range of 60 miles on a TRS? I'... I'm trying to see what I can do to improve reception without a tower going up in the back yard.

LOL. Well first of all I am at about 300 feet above sea level, and that's at least 200 feet higher than the transmissions I am receiving. I am using a discone, with low loss coax, and a filter to remove AM & FM (from ScannerMaster). I'd actually like another filter to remove TV broadcasts as well. Those powerful broadcast signals effectively lower the sensitivity of a receiver. The scanner will adjust the "hottest" signal, affecting everything. That can just make the weak signals weaker.

 

[platinumrx8]

It depends on oh so many things, like:
- The type and location of the antenna you are using
- The frequency you are trying to receive
- The terrain in your surrounding area
- The power and antenna height of who you are trying to receive
- The weather/atmospheric conditions
- Your receiver

I can only receive 800 MHz signals from about 60 miles away, and that is under the best of conditions. In any trunking system, I'll receive most of the channels just fine, but there will be 1 or 2 frequencies that are far more scratchy than the others.

The things I did to improve reception; an outdoor antenna, low-loss coax kept to a minimum length, filter out unwanted signals before they reach the scanner (AM, FM broadcasts).

the terrain is very flat where I live.. only 1 main tower for the trunking system..

But was curious how far out I can get a signal for things like, CB convos, military stuff, etc

 

[trunker0205]

Repeaterized signal 50-60 miles,simplex signal 5 miles with a decent outside antenna..

 

[platinumrx8]

Repeaterized signal 50-60 miles,simplex signal 5 miles with a decent outside antenna..

Trunker, I tried to look at your shack via your link below, but it gave me error page

 

[SkipSanders]

Basic rule of thumb for RELIABLE range at VHF/UHF frequencies is to take the square root of your antenna height above ground, in feet. That's how many miles away you 'see'. You then add the same calculation for the transmitting station, to see how far IT 'sees'. Add them together. That's your high reliability range.

It can get out to twice that, easily, at times, but only in good conditions of no hills, buildings, or foliage in the way.

Examples: Your hand held scanner: 4 feet above ground. Square root of 4 = 2. You 'see' two miles. If you were trying to hear a police officer 'direct', on his handie talkie, same for him, so, 4 miles range. (This happens to be the 'real', nevermind marketing hype, range for those GMRS/FRS bubblepack radios)

Home outside antenna at 25 feet, 5 miles.
Listening to a building/hill placed repeater at 100 feet: 10 miles.
Listening to a hill placed repeater at 2500 feet: 50 miles

These are all 'with nothing much in the way'. If there's a hill higher than you between you and the transmitter, it blocks the signal. If there's a lot of buildings or trees, same. (trees absorb UHF radio signals quite well)

Some trunk systems, usually those with a single transmitter site, have high power. Others, especially those with 5-10 transmitter sites (all same frequencies) are deliberately quite low power, and are harder to hear very far from any one of the sites.

It's a complicated question, one that cities pay a lot of money to consultants to work out in designing systems... and they STILL usually get it wrong on the first try, and have to add in sites later to cover 'dead spots'.

 

[slicerwizard]

Those powerful broadcast signals effectively lower the sensitivity of a receiver. The scanner will adjust the "hottest" signal, affecting everything. That can just make the weak signals weaker.

Strong signals should only affect reception in one band. The AGC circuit doesn't see out of band signals (e.g. VHF TV, while tuning UHF or 800/900), as the front end filters block them.

 

[hotdjdave]

Theoretically, you could hear signals thousands of miles away with the proper conditions.

However, to pick up normal local transmissions, it really depends, as others have written. The most important ones are your location and antenna; and the transmit site location (antenna site), power of transmission signal, and frequency (some frequencies tend to travel further in certain conditions and others tend to travel further in other conditions - lower frequencies travel further without obstructions and higher frequencies travel through obstructions better).

There is a more in depth answer, but the basics have been written out for you.

See this article on propagation.

 

[gmclam]

Strong signals should only affect reception in one band. The AGC circuit doesn't see out of band signals (e.g. VHF TV, while tuning UHF or 800/900), as the front end filters block them.

I did not mean to imply that one strong signal would affect everything across the spectrum. FM broadcasts (88-108MHz) certainly caused a reduction in my VHF sensitivity (below about 174 MHz) and I expect that TV broadcasts are affecting my reception in their respective bands.

 

[hotdjdave]

Strong signals should only affect reception in one band. The AGC circuit doesn't see out of band signals (e.g. VHF TV, while tuning UHF or 800/900), as the front end filters block them.

It also depends on what you define as a "band."

ITU Bands:

[U]Band    ITU   Freq          [/U]
ELF     1     3–30 Hz
SLF     2     30–300 Hz
ULF     3     300–3000 Hz
VLF     4     3–30 kHz
LF      5     30–300 kHz
MF      6     300–3000 kHz
HF      7     3–30 MHz
VHF     8     30–300 MHz
UHF     9     300–3000 MHz
SHF     10    3–30 GHz
EHF     11    30–300 GHz

E = Extremely
S = Super
U = Ultra
V = Very
LF = Low Frequency
MF = Medium Frequency
HF = High Frequency

 

[gmclam]

The scanner's "bands" ....

It also depends on what you define as a "band."

If you look at the schematic for your scanner (at least mine), it has several circuits in the RF front end; each tuned to pass a specific "band" of frequencies. Each of these "band pass filters" will reject signals outside the tuned frequencies, and only signals that pass through will be received and affect AGC.

So at least MY definition of a band is the individual ranges each scanner tunes to. Now if you're trying to listen to the AIR band (108-137MHz), it is very likely commercial FM broadcasts (88-108MHz) will affect that "band". And if you're listening to VHF HI (137-174 MHz), it is very likely VHF TV (channels 7-13) broadcasts will affect that "band". UHF TV (470-806MHz) is pretty much intermixed with public safety radio, depending on your area.

 

[hotdjdave]

If you look at the schematic for your scanner (at least mine), it has several circuits in the RF front end; each tuned to pass a specific "band" of frequencies. Each of these "band pass filters" will reject signals outside the tuned frequencies, and only signals that pass through will be received and affect AGC.

So at least MY definition of a band is the individual ranges each scanner tunes to. Now if you're trying to listen to the AIR band (108-137MHz), it is very likely commercial FM broadcasts (88-108MHz) will affect that "band". And if you're listening to VHF HI (137-174 MHz), it is very likely VHF TV (channels 7-13) broadcasts will affect that "band". UHF TV (470-806MHz) is pretty much intermixed with public safety radio, depending on your area.

Yep :wink:

Scanners have different split points to define what set range of frequencies it will reject frequencies from another split. I guess you could call these "bands." Just like there is the "UHF TV-band" (470-571 MHz and 882-960 MHz) and "VHF airband" (108-137 MHz AM), as you mentioned.

 

[BaLa]

What kind of antenna set up are you using to get a range of 60 miles on a TRS? I'm about 15 miles south of St. Louis and cannot receive their TRS. This is using a pro-94 and the 800 mhz antenna from RadioShack. I'm trying to see what I can do to improve reception without a tower going up in the back yard.

The St. Louis TRS sux..

 

[muhockey86]

I'm probably out of luck...no chance of any antenna going up on the roof or on a tower.....best I could do is one in the attic.

 

[platinumrx8]

Just curious, but do different scanners have different freq finding abilities, even if they are capable of scanning the same ranges? For instance..

if 10 different scanners can scan the 800-850 range, does that mean each will be able to pick up freqs like.. 800.0111, 825.1250, 825.1251?

 

[gmclam]

For instance.. if 10 different scanners can scan the 800-850 range, does that mean each will be able to pick up freqs like.. 800.0111, 825.1250, 825.1251?

I have not seen a "scanner" that can tune to ANY frequency, such as those you list ending in 1. Within each band of the scanner, there is a "step" amount. It could be 5khz, 6.25khz, 7.5khz, 8.33khz, 10khz, etc.

Between the programmable scanners I have listed below the PRO-97 can tune to specific frequencies that the others can not; because it is newer. There are also frequency ranges it can receive the others can not.

Regarding those who want to receive St. Louis TRS...
It sounds like you are 15 miles from the site; and it is an 800MHz signal. In that situation you should be able to use a highly directional antenna to get the signal. A highly directional antenna will have gain that you do not get with an omni-directional. Put such an antenna in the attic (or roof) and use low loss coax. What have you got to lose? I do not have a recomendation for such an antenna, but I'll bet someone in the antenna forum does.

Good luck.

 

[Aces]

Discone

I had a 40 ft tower with a AOR3000A scanner using a Radio Shack discone and their bnc coax cable hooked up in the city of Springfield, Il . I was constantly wondering what was wrong with my setup. I could only pick up a few stations in my area. I would punch in a lot of frequencies from cityfreq.com and yet I would receive nothing. I was constantly reading how well this scanner was yet for some reason my scanner was a dud. Even at night time I would try and receive stations in the 5 MHZ - 20 MHZ band. Still nothing.

After reading about the positive responses with the Diamond D130j discone with the N-connector, I decided to buy it. I also bought the Andrew heliax with N connectors. I can now say WOW. I can pick up everything in the city as well as listening at night time on the lower bands to coversations in Ohio, North Carolina, New York, Florida and many other states using just the discone and the AOR 3000A.

As can now be seen. I was having major losses due to the cable and to a lesser extent the quality of the discone. My main point is to buy the best cable and antenna you can afford and then go from their.

Regards, John