Refers to any frequency below 530kHz. Especially those in the 160 to 190kHz region.
Type of signal modulation used by a transmitter and the receive mode that must be used to hear this type of signal properly. Basically an AM signal that only uses a half, or one side, of the frequency wave to modulate the data signal. In this case, the lower side is used. Generically referred to as single sideband(SSB) and complements upper sideband(USB).
By using the two sides of the same frequency signal(upper and lower), two transmitters can use the same frequency without interferring with each other. This operation saves frequency bandwidth.
LSB frequencies are typically found in the HF band as well as on frequencies used by amateur radio.
See AM, DEMODULATE, RECEIVE MODE, SSB & USB
Those frequencies between 300 and 3000kHz(or 300kHz and 3MHz).
Typically referred to as the AM broadcast band found on most car and home radios. Covers 530 to 1700kHz.
See BANK & CHANNEL
To hear the intended data signal properly, the receiver must demodulate the received transmission using the same mode that was used to transmit it.
See DEMODULATE & RECEIVE MODE
Special type of filter found only a very few radios. Use of this mode demodulates a normal AM signal but uses a tighter filter. If there are several signals very close together in frequency, use of this mode and its more restrictive filtering will help to block out adjacent signals providing better reception of the desired signal.
See AM, DEMODULATE & RECEIVE MODE
See NOISE BLANKER
Type of signal modulation used by a transmitter and the receive mode that must be used to hear this type of signal properly. This mode is used for most VHF & UHF transmissions. Usually referred to as simply FM.
See FM, MODULATE, RECEIVE MODE & WFM
A rechargeable battery. Some scanners use a proprietary or custom battery pack from which they receive their power. Others can use regular AA rechargeable cells.
Once depleted, they can not be used until they have been recharged.
While the up-front cost is much more per cell, the ability to recharge the cell hundreds of times saves money in the long run. However, to see these savings, the cells must be treated properly. Doing so will usually permit 300-500 recharge cycles depending on the battery. Careless use can easily lower this to 100-200 cycles.
Ni-cads come in many flavors. There are basic cells which provide a minimun power rating of 600mAh and there are the high-capacity types which can provide 800 - 1000mAh.
Unlike AA cells which have a long shelf life, ni-cads discharge rather rapidly(usually about 30-45 days) when left unused. Care must be taken to see that they do not sit uncharged for too long lest they become unusable.
See NI-MH
A more recent development in rechargeable battery technology. Ni-Mh cells provide around 25% more power than a comparable Ni-Cad, cost about 1.5 - 2 times as much and only have half the number of recharge cycles.
Ni-Mh cells are much more finicky when it comes to being properly charged when compared to Ni-Cads.
See NI-CAD
Pulse-type noise is usually created by separated spark discharges like those used on automobile ignition systems.
Scanner specifications usually list two figures measured in ohms. One is the load presented to the antenna at the BNC connector(usually 50 ohms). The second is referenced to the speaker and/or earphone jack(usually 8 ohms).
See CTCSS
See CO-AX & DISCONE
Too much amplification can produce intermodulation.
See INTERMODULATION
Any signal which interferes with normal receive operations. RFI can be created by almost any electrical device including computers, TVs, radios, VCRs, microwaves, hair dryers, cable TV lines, power tools, and so on. All of these devices radiate energy which can interfere with the reception process of a radio receiver.
When a receiver comes across such a radiated signal, it might be detected as a valid transmission without modulated data. This process might interfere with the reception of programmed channel frequencies. It might also pose a source of frustration when searching for new signals since the receiver will stop on these errant transmissions.
See ATTENUATE, CO-AX & RG-6
See ATTENUATE, CO-AX & RG-8
Cables of this type are typically labelled as RG-8/U or RG-8X
See ATTENUATE, CO-AX & 9913
To hear the intended data signal properly, the receiver must demodulate the received transmission using the same mode that was used to transmit it.
See AM, CW, DEMODULATE, FM, MODULATE, SSB & WFM
If the gain control is automatically adjusted by the radio, it is referred to as automatic gain control(AGC).
See AGC
See CHANNEL, STEP SIZE & VFO
See SEARCH
Just like your car radio, you can save your favorite "stations" in memory channels but a scanner typically has hundreds of channels. Most scanners also allow you to search through the frequency spectrum for active signals just like the seek function on your car radio.
Radio Shack, RELM and Uniden make what can be called "true" scanners. Scanners differ from communications receivers in that they usually have no VFO and pre-defined receive modes and step sizes which can not be changed. They usually scan and search much faster too. They usually do not cover the HF spectrum.
See COMMUNICATIONS RECEIVER
This search is usually conducted between a user-specified lower and upper frequency limit. As each frequency is tested, the next frequency is chosen by adding the step size to the frequency just sampled. This continues until the upper frequency is reached at which point the process starts over at the lower frequency limit.
See SCAN STEP SIZE
The frequencies that are to be skipped are typically kept in a separate part of memory. Some radios allow this memory to be viewed and edited. The number of frequencies this memory can hold varies widely from 10 to 1000 based on the model and manufacturer.
See LOCKOUT
Receivers designed with better selectivity are typically more expensive.
The squelch is usually set to a minimum level to allow any strength signal to be heard. But there are some circumstances where a higher level is necessary for productive reception.
Receivers with CTCSS/DCS may control the squelch with tones/codes rather than by signal strength.
See CTCSS
See SQUELCH
Type of signal modulation used by a transmitter and the receive mode that must be used to hear this type of signal properly. Basically an AM signal that only uses a half, or one side, of the frequency wave to modulate the data signal. Collectively referred to as single sideband, it consists of upper sideband(USB) and lower sideband(LSB).
By using the two sides of the same frequency signal(upper and lower), two transmitters can use the same frequency without interferring with each other. This operation saves frequency bandwidth.
SSB frequencies are typically found in the HF band as well as on frequencies used by amateur radio.
See AM, DEMODULATE, LSB, RECEIVE MODE & USB
The wider the frequency coverage of the receiver, the more step sizes it should have. Each frequency band is typically assigned a step size for adequate channel spacing. Receivers with many step sizes are more flexible and usually allow the user to select the step size to be used.
See BANDPLAN, SEARCH & VFO
See APO & CLOCK
The first TrunkTracker, the BC235XLT, was released in May, 1997. The second was the BC895XLT released in September, 1997.
See TRUNKING
Using this methodology, a single conversation can take place on multiple frequencies which effectively mimics frequency hopping. In a system used by many agencies, it can be near impossible to follow a single conversation with a conventional scanner.
Trunked radio systems are developed, installed and managed by Motorola and GE/Ericson.
See TRUNKTRACKER
Those frequencies between 300MHz and 3GHz.
Type of signal modulation used by a transmitter and the receive mode that must be used to hear this type of signal properly. Basically an AM signal that only uses a half, or one side, of the frequency wave to modulate the data signal. In this case, the upper side is used. Generically referred to as single sideband(SSB) and complements lower sideband(LSB).
By using the two sides of the same frequency signal(upper and lower), two transmitters can use the same frequency without interferring with each other. This operation saves frequency bandwidth.
USB frequencies are typically found in the HF band as well as on frequencies used by amateur radio.
See AM, DEMODULATE, LSB, RECEIVE MODE & SSB
Some models come with more than one VFO.
See COMMUNICATION RECEIVER, RECEIVE MODE, ROTARY CONTROL & STEP SIZE
Those frequencies between 30MHz and 300MHz.
Those frequencies between 10 and 30kHz.
See WX
Type of signal modulation used by a transmitter and the receive mode that must be used to hear this type of signal properly. This mode is used for FM broadcast and TV audio signals.
See FM, MODULATE, RECEIVE MODE & WFM
See WEATHER ALERT
