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Lite info för den som kan engelska :
Varför Scanning ?
Är scanning tillåten ?
Vilken scanner ska man köpa ?
Vad är CTCSS and DCS Tone Squelch ?
Hur bestämmer jag CTCSS or DCS koden ?
Scanner Antenner
Koaxialkabel
Modifiering av scanners
Frekvensinformation
Frekvenssökning
Scannerklubbar och Mailinglistor
Uniden 3000 och 9000


Varför Scanning?

Every day and night, scanner hobbyists are entertained by what they overhear on their radios. Police cars, fire engines, ambulances, airplanes, armored cars, trains, taxis, and buses are all equipped with radios and you can listen to them. You can monitor the local sheriff and fire departments to hear about events "as they happen," before the news reporters hear about them. Hostage dramas, bank robberies, car crashes, chemical spills, neighbor and domestic disputes, tornado sightings are all fair game. In a single afternoon, you can hear a high speed police chase, Drug Enforcement agents on a sting operation, and undercover agents as they stakeout a suspect. How about listening to a team of G-men protect the president while transmitting in the 167 MHz range? Baby monitor intercoms are actually transmitters and you can hear them between 49.67 and 49.99 MHz. Stay ahead of road conditions by listening to highway road crews, snow plows, and traffic helicopter pilots. Many midwesterners monitor the state police and and county sheriff to learn of approaching tornados long before warnings are broadcast on TV and commercial radio. Take your scanner to sporting events and listen to race car drivers, football coaches, etc., in the 151, 154, and 468 MHz ranges. Monitor the everyday hustle and bustle of businesses, from cable TV repair crews tracking down pirate descrambler boxes, to security guards at your nuclear power plant or mall security guards chasing a shoplifter.

Är scanning tillåten?  (I Sverige, ja)

In the United States, scanning from your home or at work is perfectly legal in most situations. Speaking of privacy, federal law also requires you to keep what you hear to yourself and not use the information you hear on your scanner for personal gain.

Vilken scanner ska man köpa ?

Radio Shack and Uniden (maker of Bearcat, Regency, and Cobra brands) offer a wide choice of scanners. Radio Shack scanners are actually manufactured by both GRE (General Research Electronics) and by Uniden. Personally, I don't recommend Trident nor many of the AOR brand scanners, although the AR8000 and AR3000 have good reputations and the AR5000 works well. Programmable (synthesized) units have replaced crystal controlled models as they don't require crystals and usually have a keypad that permits you to store frequencies into channels. Programmables are now so cheap it doesn't make sense to buy a crystal unit as your main scanner unless you get it for under $45 or so. You can get a battery operated hand held scanner, a bigger "base" scanner which is powered from an AC outlet, or a mobile scanner which connects to your auto's electrical system. There are tradeoffs -- base and mobile scanners have larger displays and almost always provide more audio than portables, and some portables are more prone to interference when connected to outdoor antennas than base models. But when severe weather knocks out the power in your home, there's nothing like having a battery operated scanner to monitor the power utility and police frequencies! Make sure your first scanner has a "search" feature, which allows it to search all the frequencies between two frequency limits of your choosing. Beware of low cost programmables which can't search. Get a model which covers the 900 MHz band. Usage of the 800 - 950 MHz band is growing fast and you will miss out on the action unless your scanner covers this band. If you're not sure whether you'll like scanning, don't want to spend much money, a 50 channel scanner will do. In general, the more channels and banks, the better. Most of the action takes place on frequencies between 30 and 1000 MHz, so don't be misled by scanner models boasting coverage from 3 to 2000 MHz. There's currently not much to monitor in the 1000 - 2000 MHz range. If you are interested in receiving short wave, that is, signals in the 3 - 30 MHz range, it's best to get a short wave radio specifically designed for that purpose. Although some scanners receive the short wave band, their performance in that range is often second rate. The $2000 Icom R8500 and AOR AR5000 models are exceptions. Deluxe scanners can be controlled and/or downloaded by a personal computer, a feature which appeals to a small but growing number of scanner owners. Almost all low and mid-priced scanners are prone to receiving images -- receiving the same signal erroneously on two or more frequencies. With a few exceptions, images are unwelcome due to the interference they cause, e.g., hearing aircraft transmissions while the scanner is tuned to the local police frequency. Premium quality scanners use "up conversion" circuitry, a scheme which greatly reduces, but does not eliminate, image reception. A number of owners report problems with the Icom R1 portable.The Uniden BC9000XLT base and BC3000XLT portable work very well and are my current favorites.

Vad är CTCSS and DCS Tone Squelch ?

Upscale scanners can be optioned with a subaudible tone decoding squelch circuit. There are two types: CTCSS (Continuous Tone Coded Squelch System) and DCS (Digital Coded Squelch). In simple terms, this feature lets your scanner ignore signals you don't want to hear. Most land mobile two way radios, except trunked systems, transmit either CTCSS or DCS signals subaudibly along with the voice information. U.S. military field radios employ wider deviation and a 150 Hz CTCSS tone, not supported by most scanners or CTCSS decoders. There are over 40 different CTCSS codes and you can program a specific CTCSS or DCS code into each memory channel. Using a CTCSS or DCS decoder permits your scanner to open the squelch only if the transmission has a code which matches the code you program. CTCSS and DCS decoding offers several advantages: 1. Ignore unwanted signals on shared frequencies: It is common for several users to share the same frequency, e.g., my county sheriff uses the same frequency as Chicago Police, located about 60 miles away. I want to hear my sheriff's transmissions but don't want the scanner to stop on or listen to Chicago Police transmissions. This is especially a problem when radio propagation is good, e.g., during a "band opening," when reception range is temporarily increased. 2. Combat intermodulation interference: Helps keep out intermod and image interference from strong pagers and other signals which are not transmitted with a matching code. 3. Ignore scrambled transmissions: Many federal law enforcement agencies (FBI, Secret Service, etc) and some local police agencies employ digital voice scrambling, which sounds like white noise and is annoying to hear. The CTCSS or DCS code is sent only when the station is transmitting unscrambled, or "in the clear." You can program federal frequencies along with the proper code into your decoder-equipped scanner so you won't have to listen to the scrambled mess and only hear their transmissions when they are unscrambled. CTCSS also goes by various tradenames: Motorola's PL (Private Line), GE's Channel Guard, and RCA's Quiet Channel. Motorola uses the tradename DPL (Digital Private Line) for its digital coded squelch.

Hur bestämmer jag CTCSS or DCS koden?

There are a few ways to determine the CTCSS or DCS code transmitted by a station: 1. Use an outboard CTCSS/DCS reader which must be attached to the discriminator output circuitry inside the scanner. The reader has an LCD or LED display which indicates the code when a station transmits. I use a CSI model CD-1 Communications Decoder Unit, an an excellent reader which sells new for about $200. (Connect Systems Inc., Ventura, CA, 800-545-1349, www.connectsystems.com). 2. Many of the ScannerMaster guides, as well as scanner club newsletters, print the CTCSS codes used by transmitting stations. 3. On some scanners equipped with the CTCSS squelch, you can program into memory the frequency of interest. Then you "tune" slowly through all the different CTCSS and/or DCS codes until the squelch opens and you hear the dispatcher talking. This is a slow process and the station has to keep transmitting during it. 4. A slow, brute force method is to program the same frequency but a different CTCSS code into several channels and see where your scanner stops. 5. In some cases, I've actually examined the walkie- talkies I want to monitor and found the CTCSS code printed on a label on or inside the radio.

CTCSS Tones
"CTCSS tones, sometimes called sub codes or privacy channels, uses a sub-audible tone to prevent other people using the same channel from interrupting your conversation. Most radios have 38 available CTCSS (Continuous Tone Coded Squelch System) codes which can be individually assigned to any of 14 channels, for a total of 532 combinations.
Once activated, the sub-audible tone is transmitted each time the PTT (push-to-talk) button is pressed. Additionally, the radio only responds to incoming signals using the same CTCSS tone." The above text was taken from the GE 35840 user's guide.
NOTE: This feature does not keep anyone from hearing your conversation. It simply "filters-out" anyone's transmission that does not have the same channel/code combination set.

Scanner-antenner

All scanners come with a built in antenna, permitting reception up to about 20 miles or so. Portable scanners are supplied with a helical (spring shaped) antenna, covered by rubber. The rubberized antennas furnished with current models are too stiff and place stress on the antenna jack. Older scanners to be supplied with more flexible antennas. I prefer these alternative antennas for use with portable scanners: 1. The Icom FA-1433B dual band flex antenna, a thin and very flexible rubber antenna, is slightly longer than a stock heliflex but provides better performance. 2. The Austin Condor is a 12" long rubberized antenna available for about $30. While considerably longer than the stock antenna and the FA-1443B, the Condor is very flexible and provides VHF-high band reception superior to both. It is not designed to cover the VHF-low band, but will allow reception there at least as good as shorter antennas. The Austin Condor is available from Grove Enterprises. 3. The "Thin-Stick" is an 18 inch telescoping antenna for extended range. It is made in USA by Smiley Antenna Co., Inc. and is designed to cover both the 2 meter and 220 MHz bands, but its variable length means it can be adjusted for optimum performance on other bands. What makes the Thin-Stick different from an ordinary telescoping antenna is the spring between the antenna and the connector portions. The spring absorbs most of the impact if the antenna collides with an object. The street price is about $17 and it is available from Amateur Electronic Supply, Milwaukee and other retailers. Outdoor antennas, like the Channel Master 5094A (available from Amateur Electronic Supply) or Antenna Specialists AV- 801 (recently discontinued), can extend reliable reception to 50 miles or more, depending on terrain. If you do use an outdoor antenna, be sure to disconnect and ground it during storms and when not in use to avoid a lightning hazard. Discone and ground plane type antennas can be more prone to cause scanner damage due to static charge buildup because they are not at "DC ground."

Koaxialkabel

If your antenna installation requires more than 50 feet of feedline, use RG213/U or high quality RG8/U coaxial cable. RG213/U, e.g., Belden type 8267, has a non-contaminating jacket and will last longer. Each has an outer diameter of about 13/32". Similarly sized Belden 9913 cable and clones have lower attenuation but are difficult to bend, require special connectors, and can accumulate moisture inside because they are hollow. If you must use a small diameter cable for long runs, use RG6/U. Avoid RG58/U (7/32" OD) due to its losses at high frequencies. RG8/X (1/4" OD) is suitable for short patch cords.

Modifiering av scanners

The term "mod" is often used as shorthand for "modification." If you are handy with a soldering iron, you may be interested in modifying ("modding") your scanner to add features or enhance its performance. Be warned this usually voids your warranty and current models are difficult to service due to the small, delicate surface mount components. By federal regulation, new scanner models cannot be easily modified to tune the cellular phone bands. The term "mod" has been narrowly used by some people to mean a change which permits a scanner to receive cellular phone frequencies. This definition is far too restrictive as there are several ways one could modify a scanner, e.g., changes to improve audio quality, adding an S-meter, expanding the number of channels, changing the earphone jack to accept stereo headphones, etc. Modification article files can be copied from several ftp sites including the /pub/hamradio/mods directory at: garfield.catt.ncsu.edu oak.oakland.edu (IP address 141.210.10.117) Modification articles posted on Usenet seem to have a life of their own. Frequently, they are plagiarized from the Internet and compiled by book, CDROM, and magazine publishers, sometimes reworded, then sold. Hobbyists then copy the modifications from the books, CDROMs, and magazines back onto the Internet or BBSs (bulletin board systems)!

Frekvensinformation

To avoid chaos, the FCC licenses two-way radio users and assigns them specific frequencies. Groups of frequencies are allocated to specific types of users, so you won't usually find fire departments using the same frequencies as taxi drivers, for example. Scanner enthusiasts can obtain frequency information from several sources, including books, government microfiche records, or other listeners. Industrial customers use RadioMap reports to survey the "radio environment" prior to installation of radios and wireless microphones at customer sites. RadioMap is used by the maritime and broadcast industries, as well as ham radio operators to solve intermod interference problems, and has been very favorably reviewed in RCMA Scanner Journal, American Scannergram, and USSN.

Frekvenssökning

When you try listening to a frequency for the first time, you'll want to know who you're hearing. Although FCC rules require radio systems to identify their operations with their assigned call letters either automatically or verbally, most ignore the regulation. This often makes it difficult to know who is transmitting. Moreover, many radios are now being placed in service illegally, without first obtaining the required FCC license. There is a challenge in deriving new spectrum usage information on your own. Sometimes it requires several days of listening, taping, and compiling fragments of information. Other times, the frequency information is there for the taking - without hassle. You can approach from two directions: 1. Listen first: Monitor a frequency or frequencies, and try to determine who's transmitting and what purpose the channel serves. Once you identify the user, log the information. 2. Compile first: Take advantage of opportunities, such as examining the frequency label on a guard's radio, or reading the FCC license hanging on the "radio room" wall, to compile frequency lists, then monitor the listed frequencies to confirm that they are really in use. Readers are urged to abide by the rules of good taste and local laws in the quest for frequency information. Don't trespass, wait for an invitation. Most listeners use a combination of both approaches. You can examine the FCC license on premise. I have found the actual FCC radio license, complete with frequency assignments, hanging on the walls of places like the mall security office or company guard shack. You can examine the labels on radio equipment. Frequency information is engraved on labels on the back of many walkie-talkies, or inside the battery compartment, like in the Motorola HT220 model. Most pagers have labels on the bottom or inside. Like passwords taped onto terminals, it's not uncommon to find labels embossed with frequencies or call letters glued to the front of base stations. You can make your own opportunities for eyeing the equipment or take advantage of "open house" events. If information is displayed publicly, then a reasonable person could assume it's not government secret. Hobbyists are urged to exercise a modicum of restraint and good judgement, however. If you don't know the exact frequency, but have a general idea of the range (e.g. 150 - 152 MHz), use your scanner's "search" mode. Most programmable scanners afford the ability to search between two frequency limits set by the user. A few models, like the ICOM R7000/R7100, and R1, and older Bearcat 250 and Regency K500, have the ability to automatically store active frequencies found during an unattended search operation. To find the frequency of a hotel communications system, one fellow installed his Bearcat 250 in his car and parked in the hotel lot, leaving the scanner in the "search and store" mode. He left the antenna disconnected so the scanner would only respond to a transmitter in the immediate vicinity. Aside from a scanner and antenna, the most useful piece of equipment for sleuthing is a voice actuated (VOX) cassette tape recorder. You don't need a high fidelity model or anything fancy, a Radio Shack CTR-82 will do. It's best to use a shielded, attenuating cable to feed the scanner audio into the recorder rather than relying on the recorder's internal microphone. VOX recorders allow one to compress a whole day's worth of monitoring onto a single tape. I often leave a recorder "armed" and connected to a scanner at home while I am at the office or doing something else. When call letters are mumbled, I can play and replay the tape until I hear and understand them. Test equipment can aid in the quest for new frequency information. I've used a spectrum analyzer connected to an outside antenna, and a frequency counter for close-in work.

Scannerklubbar och Mailinglistor

One of the best parts of the hobby is sharing it with other radio buffs. Trading information with other hobbyists about frequencies, communication systems, and receiving equipment is more valuable than any pile of magazines.

Newsgroups: rec.radio.scanner, alt.radio.scanner, rec.radio.info, sci.electronics.repair. Subject: Repair Tips for Bearcat Scanner Radios.

 

 
 

 

 
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