Author Topic: Is the era of scanner listening really gone?  (Read 3763 times)

Offline weirdal

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Is the era of scanner listening really gone?
« on: January 30, 2007, 04:48:48 PM »
I always hear about how it's nearly impossible to hear phone conversations over a scanner these days. I don't understand this because I can generally pick up a conversation within 5 minutes here if I try. It's all on the 896-920mhz range, just past the blocked 800 freqs.

Are there other people out there that still listen on a scanner, or is it just me? I do live in the middle of buttfuck nebraska, so It wouldn't suprise me that people are still using older phones around here...

Offline amazing_ned

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Re: Is the era of scanner listening really gone?
« Reply #1 on: January 30, 2007, 06:12:04 PM »
There's tons to listen to, especially if you have a scanner (or ham radio) with a large receive range. The phone conversations you are finding are only 902-920 MHz, that is the range for the 900 MHz cordless phones (and, I think, the 33 cm ham band), a lot of people have been moving to 2.4 GHz and 5.x GHz phones recently, mostly because they like to jerk each other off about technology they don't know about (OMG MOR HERTZZZ!), especially in yuppie suburban areas. Usually you are able to find the older phones in larger cities with a good segment of older, established population. Lots of them hold on to their antiquated phones, but your best bet is 900 MHz or 2.4 GHz (they do make those really high frequency receivers, but generally the higher frequency the smaller workable range). The most that I've found recently in the 900 MHz band has been baby monitors (you can always monitor the going-ons of that household too, it's slightly amusing).

Plus, you have toooons of other shit to listen to with any decent scanner.

Offline Godot

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Re: Is the era of scanner listening really gone?
« Reply #2 on: January 31, 2007, 03:46:18 PM »
No, not at all.

Many people still use 900 MHz analog cordless phones, and even 49 MHz cordless phones. Many of the hotels with cordless phones use outdated phones, so the next time you are in (or near) a hotel with cordless phones, pull out your scanner.

If you have an old/modified radio that can pick up in the analog cell phone range, you can hear all those people talking with outdated, you can hear people with old phones. In fact, if you have an old Motorola phone that you can put in test mode, you can interfere with those people, too. I'll have to post a recording of that sometime.
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Offline El_Gato_Negro

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Re: Is the era of scanner listening really gone?
« Reply #3 on: February 02, 2007, 11:18:49 PM »
I hope not! I just bought my first scanner. And I came here to try and learn some tips. If your neighbor is only 10-feet away from you and your scanner, would that have any bearing on anything? As you can see, I'm greener than the Grinch at Christmas.

I just picked up a little hand-held deal from eBay for cheap, mainly just to entertain myself. I don't know a thing about it, except it is a pro-96 something or other. I figured I could at least try to hear police/fire calls.
Bless you.

Offline amazing_ned

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Re: Is the era of scanner listening really gone?
« Reply #4 on: February 03, 2007, 08:29:24 AM »
The closer your neighbors the better, the 33cm range (902-928 MHz) has a decent reach.

Offline immabadspellor_

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Re: Is the era of scanner listening really gone?
« Reply #5 on: February 04, 2007, 08:30:15 AM »
Those 2.4GHz phones go pretty far.  The nice thing about 2.4GHz is that it is very easy to build a very high gain directional antenna and if you're in an area with good line of sight you can pick up these things for quite some distance.  Unfortunately most scanners that cover up to that high of a frequency have piss poor sensitivity up there but with these surplus wireless cable TV downconverters I picked up off of eBay for a few bucks you can pick them all up at around 130MHz or 430MHz depending on the model you get.  It works great!

Offline amazing_ned

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Re: Is the era of scanner listening really gone?
« Reply #6 on: February 04, 2007, 11:08:04 AM »
Please elaborate

Offline immabadspellor_

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Re: Is the era of scanner listening really gone?
« Reply #7 on: February 04, 2007, 04:19:50 PM »
Please elaborate

Alright.  There used to be something called MMDS or "wireless cable" that was somewhat commonplace in certain areas around the US and beyond.  Some places may still be using it but now that a lot aren't, there's a lot of MMDS junk being torn down from peoples' houses and put up on eBay.  The cable head end instead of running hardline down the road would just put up a big tower (or rent space off one) and transmit their entire offerings over the air.  The stations were transmitted in analog but at a much higher frequency than TV sets can pick up normally.  The frequency was between 2 and 3 GHz depending where in the world it was.  The user was provided with a BBQ dish antenna that had a downconverter at the focal point of the dish. 

http://en.wikipedia.org/wiki/Image:Mmds_dish1.jpg

The downconverter has a single F connector on it that outputs on frequencies a normal TV can pick up (as well as most scanners!) and power is also supplied via that same coax run.  These BBQ dish antennas have great gain but they also cost a boat load if you have to have it shipped buying it off of eBay.  You're better off just nabbing the downconverter and using it with a spare 18" satellite dish you see laying in a dumpster. 

As I mentioned, these devices are powered through the coax.  This is easily enough accomplished by building or buying a bias T.  The object is to feed voltage to the downconverter without having it fed into your scanner as well, just passing the signal to your scanner alone.  There are construction plans all over the internet if you do a google search as it's literally about 4 parts.  You can improvise one using a TV splitter and a DC block.  If you have a mast mount TV amplifier that has one of those power injectors, that power injector is a bias T with the power supply.  I see these show up on eBay for cheap every now and then.  Most of these downconverters need around 12V to run, some need 17V; it depends on the model.  You can always hack out the voltage regulator to configure it for a voltage you have that's more handy.  I think the guts of it runs off of the usual 5V anyway. 

Some of these downconverters are built for frequencies slightly below the 2.4GHz cordless range so they might not have optimal gain.  A comb filter inside is usually responsible for this and fiddling around with removing it may make a world of difference.  Mine works just fine with no mods whatsoever.  It's a Pacific Monolithics PM3151-1951.  The 1951 is the LO frequency.  What this means is you take the frequency you want to listen to, lets say 2400MHz exactly, and subtract 1951MHz from it.  This gives you 449MHz, which is a frequency nearly every scanner ever made can receive.  You tune your scanner to 451MHz, you're really listening to 2402MHz!  Now 2.4GHz analog cordless phones are wide FM like analog phones on other frequencies so if your scanner only receives narrow FM the audio will sound overmodulated (clipping) especially if they're talking loudly.  These things have a good noisefloor and using one of these with a scanner will usually outperform a cheap scanner that can pick up 2.4 GHz.


Offline amazing_ned

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Re: Is the era of scanner listening really gone?
« Reply #8 on: February 04, 2007, 06:02:19 PM »
Excellent, I'll have to try this out soon. Thanks again for the info