Two Way Radios

In order to choose a two-way radio you must first decide how you want to use it. Basically two-way radios operated by most commercial users fall into two, general categories:

Use in an “On Site” Environment. This includes plants, warehouses, schools and campuses, churches, office buildings, shopping malls, just about any situation where the people who need to communicate with each other are in a relatively close setting (usually less than 1/4 mile to 3 to 5 miles, at most). This type of use can usually be accomplished with two-way radios that talk directly to each other (up to a mile or two), or, with devices called “repeaters” that are mounted on top of buildings or other relatively low structures, and "repeat" or relay the signal to get greater range (typically up to about 5 miles, but possibly more, depending on antenna height).

Most on site systems are UHF, as those signals are better at penetrating walls and other obstacles.However, rural systems that are more spread out with fewer obstacles, may be VHF, as those signals travel farther in the open.

In the past, most on site systems were analog, but today, more and more digital on site systems are being installed.

Radios and repeaters that can make up an On-Site System come from vendors such as HYT, Hytera, ICOM, Kenwood, Vertex/Standard, Ritron and others. 

Use over a Wide Area. This might be several miles, or, across a large geographical area. For most of our customers this is the Dallas Metro area, the DFW Metroplex, or North Texas. These radios work through a network we provide where the repeaters that relay the signals are on tall structures such as office building and towers. Dallas Mobile Communications currently operates and ICOM IDAS Digital Wide Area System.

See our Area Wide Tab for more information about our systems and coverages.


Just like most things you buy, (cars, trucks, tools, computers, you name it), two-way radios can range from basic, economy models, with a few features and moderately rugged, to full-featured models that are built to withstand the toughest working environments. When you buy these types of items, you have to know which one you will need for the job. Part of our job is help you to determine which model is best for your situation.

On-Site Systems and Area Wide Sytems

Repeater in an On-Site System installed in a Warehouse. Clear Communications with almost No Dead Spots. No need for cell phones and monthly payments, because it's Your System!
How an on-site repeater works. And how you can upgrade your current repeater.

Two Way Radios

ICOM IDAS Sytem Details and how it works.

by Lonnie Danchik on 02/16/11

IDAS™ System Bridges the Gap Between Analog and Digital

IDAS™ is Icom's digital land mobile radio system using the NXDN common air interface and offers a complete system of handheld radios, mobile radios, repeaters, network interface/trunking controller, IP-based virtual radio, various accessories and a complete system solution.

IDAS system features

  • IDAS calling in digital conventional mode
  • IDAS conventional IP network
  • IDAS trunking

IDAS has useful calling features including selective calling, status message, radio, stun/kill/revive and GPS position reporting, etc. The IDAS system is ideal for business and industry users who are thinking to migrate to a digital system and hence to future mandated narrow channel spacing.

IDAS conventional IP network

An IDAS conventional IP network can extend your communication coverage. It lets you connect dispersed sites and allows you to communicate like a single site.  With an IDAS conventional IP network system, it is possible to have radio communications all the way from the basement to the top floor, all in stable digital audio. Already deployed LAN cables can be used in an in-building solution.

IDAS Multi-Site Trunking

IDAS MultiTrunk extends Icom's single site trunking system to multiple sites. Although IDAS MultiTrunk builds on the technology of IDAS Multi-site Conventional, it is a huge leap in capabiltiy. With IDAS MultiTrunk the advantages of trunking are enabled across many sites separated by great distances for operations that are large and geographically dispersed.

  • Scalable from 1 channel to 30 channels per site, up to 16 sites
  • Effective operations with all channels used to transmit voice or data payload, priority monitoring for emergency interrupt, and polite roaming while conversations are occurring
  • All the features of a digital radio, like text, GPS and group/individual calls available in multi-site trunking

Digital/analog mixed mode operation

The IDAS radio can receive both analog mode and digital mode signals on a single channel. You can partially introduce the IDAS radios, while using the existing analog radios in a system. The IDAS system allows you to scale migration to narrow band digital at your own pace and need, while running your existing analog system. It is a cost efficient way to obtain the next generation two-way radio technology and protect your current system investment.

Peer-to-peer communication with FDMA

When compared to a TDMA (Time Division Multiple Access) 6.25 equivalent system, the FDMA (Frequency Division Multiple Access) enables "peer to peer" communication between radios in 6.25kHz digital mode. It ensues communication with no reduction in channel capacity, even if a repeater site is not available, or goes down.

Spectrum efficiency

As explained, the IDAS system allows you to meet US FCC narrow banding requirements, and provides a solution to overcrowded airwaves.

Digital signal advantage

When comparing digital with analog FM, the audio quality of analog FM gradually deteriorates with static noise as the distance increases. On the other hand, the digital audio provides noise-less, stable audio for longer until the fringes of the communication range.

Secure communication

When secure communication is required, the IDAS system provides a digital voice scrambler using a 15-bit key (about 32,000 keys) for encryption as standard. This is added security to the digital modulation/demodulation.

Selective call, group call and talk group ID

The IDAS system allows you to call individual or group users. IDAS radios automatically send their own ID number when the PTT button is held down. IDAS radios memorize up to  500 of both individual/group ID is displayed on the LCD while receiving a message allowing you to identify who is calling.

Talk back function and call mode selection

When the talk back function is enabled, the IDAS radio automatically selects the received talkgroup or individual ID to reply to the received call, while the talk back timer remains. After the talk back timer is exceeded, the IDAS radios will set to an initial call mode depending on programming which is either talkgroup or individual call or retain the previous user call mode selection.

Digital voice scrambler

When secure communication is required, the IDAS system provides a digital voice scrambler using a 15-bit key (about 32,000 codes) as standard. This is added security to the digital modulation/demodulation.

Emergency call function

When the emergency button is pushed, the emergency signal will be automatically sent to the dispatcher or another radio. Other emergency features are a man down feature and a lone worker function, available for automated emergency calls (in digital and analog modes). A remote radio monitor function allows the dispatcher to turn on the PTT button from a remote location and transmit anything the microphone hears for a preprogrammed time period.

Status message

You can set up to 100 conditions such as "on duty," "at lunch" or "in route" and send your status to another unit or the dispatch. Also, you can request another unit to send their status and receive it.

GPS position reporting

When used with the GPS speaker microphone, HM-170GP, for the handheld radio or an external GPS receiver for the mobile radio, the IDAS radio can send the current position information to another unit or the dispatch. Simultaneous status message and GPS data can also be sent. When connected to a PC installed with a mapping software application, the dispatcher will know the real-time activity of the fleet members.

Radio stun, kill and revive

The radio kill functions disable a lost or stolen radio over the air, eliminating security threats from undesired listeners. When the radio receives the stun command, all functions will be locked out until the revive command is received or the user password is entered. The IDAS radio can also send radio stun, kill and revive commands.

Ran (Radio Access Number) for digital code squelch

The RAN code is the digital equivalent of CTCSS for accessing an IDAS repeater or digital code squelch function.

Short data message capability

Short data messages of up to 12 characters may be sent and received between IDAS radios or from the remote communicator.

Up to 16 IDAS repeaters connection over IP network

With the optional UC-FR5000, up to 16 IDAS repeaters can be interlinked with each other. An IDAS terminal radio user can communicate with other IDAS terminal radio users belonging to the interlinked repeater sites and/or a virtual dispatch station on the network.

Low bandwidth requirement

By using the AMBE+2™ vocoder compression, an IDAS conventional IP network requires only about 13kbps bandwidth per one voice path in theory. It means a DSL class line is sufficient for the IDAS conventional IP network. The IDAS conventional IP network. The IDAS conventional network system requires only one fixed IP address in a group of networked repeaters. Other repeater sites can work with dynamically allocated IP addresses when the IP manager/client mode is enabled through some restrictions may still be applicable.

Integrated system for clean and simple installation

Icom has made it simple and easy to introduce and install an IDAS conventional IP network system requires only the UC-FR5000 network controller which can be installed into the IC-FR5000 series repeater - no control server and no extra rack space is required. In addition, the repeater and network controller settings can be remotely maintained and monitored over an IP connected PC.

RC-FS10 remote communicator

The remote communicator creates an IP-based virtual radio on a PC and works as a simple dispatch. IDAS communication features can be used with the remote communicator software. UP to 8 target IDAS repeater sites * can be programmable in the software. Eight remote communicators can connect to a single repeater
*The RC-FS10 software can transmit one voice path at a time. One CT-24 is required for receiving an IDAS repeater site and up to 8 repeater sites can be monitored simultaneously with 8 CT-24s.

Other features

  • Radio check function allows you to verify if another radio is within the communication range
  • Call log displays the received call history
  • Call alert function notifies receiving party that a call is coming with a beep sound and blinking icon
  • Base station operation for repeater
  • Late entry: IDAS radio can decode the received ID and show group ID, unit ID or alias name on the display even when turned on during a conversation.

Two Way Radio Frequencies

by Lonnie Danchik on 01/29/11

The General Mobile Radio Service (GMRS) is a licensed land-mobile FM UHF radio service in the United States available for short-distance two-way communication. It is intended for use by an adult individual who possesses a valid GMRS license, as well as his or her immediate family members.[1] Immediate relatives of the GMRS system licensee are entitled to communicate among themselves for personal or business purposes, but employees of the licensee, who are not family members, are not covered by the same license.

GMRS radios are typically handheld portable devices much like Family Radio Service (FRS) radios, and share some frequencies with FRS. Mobile and base station-style radios are available as well, but these are normally commercial UHF radios as often used in the public service and commercial land mobile bands. These are legal for use in this service as long as they are GMRS type-approved. They are more expensive than the walkie talkies typically found in discount electronics stores, but are higher quality.



[edit] Licensing

Any individual in the United States who is at least 18 years of age and not a representative of a foreign government may apply for a GMRS license by completing the application form (either on paper or through the FCC's Universal Licensing System) and paying the license fee (currently $85.00). No exam is required. A license for a GMRS system is usually issued for a 5-year term.[2] Prior to July 31, 1987, the FCC issued GMRS licenses to non-individuals (corporations, partnerships, government entities, etc). These licensees are grandfathered and may renew their existing licenses. No new GMRS licenses are being issued to non-individuals, nor may existing non-individual licensees make major modifications to their licenses.[3]

The license extends privileges of the primary licensee to include communications with the licensee's immediate family members, and authorizes immediate family members to use the licensee's station(s) to conduct the activities of the licensee. Additionally, the FCC rules allow GMRS licensees to communicate with other GMRS licensees. GMRS licensees are allowed to communicate with FRS users on those frequencies that are shared between the two services. The rules require each GMRS user family to have a license, rather than (as in the case of commercial and public safety land mobile license) authorizing a licensee's employees to use the same license.

[edit] Frequency assignments and FRS

The GMRS-only channels are defined in pairs, with one frequency in the 462 MHz range for simplex and repeater outputs, and another frequency 5 MHz higher for repeater inputs. There are eight channels exclusively for GMRS and seven "interstitial" channels shared with Family Radio Service. GMRS use requires an FCC license, and licensees are permitted to transmit at up to 50 watts on GMRS frequencies (although 1 to 5 watts is more common), as well as have detachable or external antennas.

GMRS licensees are also able to use the first 7 FRS frequencies (the "interstitial" GMRS frequencies), but at the lower 5 watt maximum power output, for a total of 15 channels. FRS channels 8 through 14 are not available for GMRS use; use of these frequencies requires an FRS transceiver.[4]

Recently, hybrid FRS/GMRS consumer radios have been introduced with 22 channels, instead of the 14 channels associated with FRS. On this type of radio, channels 8-14 are strictly license-free FRS channels. Transmitting on all channels above channel 14 requires a license. Transmitting on the shared FRS/GMRS channels 1-7 requires a license, if using more than ½-watt. It is the responsibility of the radio user to read and understand all applicable rules and regulations regarding GMRS. These hybrid radios are often referred to as "bubble pack" radios, since they are often packed in a plastic shell, for hanging on a display shelf. The massive flooding of these radios have led to a term known as "bubble-pack pirates", persons who use GMRS without a license.

The FCC rules for use of hybrid radios on channels 1-7 require licensing only when operating under the rules that apply to the GMRS. Many hybrid radios have an ERP that is lower than ½-watt on channels 1-7, or can be set by the user to operate at low power on these channels. This allows hybrid radios to be used under the license free FRS rules if the ERP is less than ½-watt and the unit is certified for FRS operation. Only two makers of hybrid FRS/GMRS radios (Garmin and Motorola) presently sell radios that will operate on the GMRS repeater channels; the common "22 channel" radios cannot be used with GMRS repeaters. The Icom IC-F21GM is a solely-GMRS radio which will also work repeaters.

Hybrid packaging still contains the notice of the FCC licensing requirement. Estimates of the number of hybrid FRS/GMRS radios sold to date range from 20 to 50 million units or more. This is compared with approximately 80,000 active GMRS licensees (per the FCC database). Enforcement against individuals is rarely, if ever, attempted. [5]

[edit] Frequency chart

The "Friendly Name" of a frequency is the portion of the frequency to the right of the decimal (the kHz portion).

This first set of frequencies shows the split frequency pairs used in duplex operational mode, often used with repeaters. Simplex (same frequency for receiving and transmitting) mode only utilizes the lower set of frequencies.

All channels are used with narrow-band frequency modulation.

Name Lower frequency (repeater output) (MHz) Upper frequency (repeater input) (MHz) Motorola convention Icom F21-GM convention Notes
"550" 462.550 467.550 Ch. 15 Ch. 1
"575" 462.575 467.575 Ch. 16 Ch. 2
"600" 462.600 467.600 Ch. 17 Ch. 3
"625" 462.625 467.625 Ch. 18 Ch. 4
"650" 462.650 467.650 Ch. 19 Ch. 5 Use not permitted near the Canadian border.
"675" 462.675 467.675 Ch. 20 Ch. 6 Suggested nationwide emergency and road information calling. Nationally recognized coded squelch for 675 emergency repeater operation is 141.3 Hz.
"700" 462.700 467.700 Ch. 21 Ch. 7 Use not permitted near the Canadian border.
"725" 462.725 467.725 Ch. 22 Ch. 8

This second set of frequencies shows the interstitial ranges shared with the Family Radio Service services. These frequencies can only be used for simplex operations.

Name Frequency (MHz) Motorola convention Icom F21-GM convention Notes
"5625" or "FRS 1" 462.5625 Ch. 1 Ch. 9
"5875" or "FRS 2" 462.5875 Ch. 2 Ch. 10
"6125" or "FRS 3" 462.6125 Ch. 3 Ch. 11
"6375" or "FRS 4" 462.6375 Ch. 4 Ch. 12
"6625" or "FRS 5" 462.6625 Ch. 5 Ch. 13
"6875" or "FRS 6" 462.6875 Ch. 6 Ch. 14
"7125" or "FRS 7" 462.7125 Ch. 7 Ch. 15

Note 1: The Personal Radio Steering Group (PRSG) and Popular Wireless Magazines adopted CTCSS 141.3 Hz as the national travel tone for use on all GMRS channels. It is not known how many GMRS licensees have adopted the standard.

Note 2: Some groups have recommended FRS Channel 1 as a national emergency/calling channel, such as REACT (Radio Emergency Associated Communications Teams) and the National SOS Radio Network.

[edit] History

The predecessor to GMRS was named Class A Citizens Radio Service when it was rolled out in the 1960s. Tube type transceivers were used, and transmitter power was limited to 60 watts (plate input power to the final amplifier tube). The original service ran wideband FM with ±15 kHz transmitter deviation and 50 kHz channel spacing. At the time, this was the norm for all U.S. land mobile services. There was also a Class B Citizens Radio Service which used a different set of 461 MHz channels and was limited to 5 watts output. Business users were permitted to license in this radio service. Radios were built by consumer electronics firms and commercial two-way radio vendors.

In the 1960s, the UHF 450-470 MHz band was re-allocated to 25 kHz channels. This meant transmitter deviation was reduced to ±5 kHz. This doubled the number of channels available across the entire 450-470 MHz band. Class B Citizens Radio Service channels were re-allocated to other radio services.

In the 1970s, allowed power was again changed to 50 watts across the output terminals of the transmitter. In 1987, licensing of business users was discontinued and businesses were allowed to continue operating until their licenses expired. There was congestion on all channels in larger metropolitan statistical areas and moving businesses to Business Radio Service channels would provide some relief. The radio service was changed to its present name.

[edit] Use of GMRS equipment in other countries

The use of radio transmitters is regulated by national laws and international agreements. Often radio equipment accepted for use in one part of the world may not be operated in other parts due to conflicts with frequency assignments and technical standards. Some of the roles that the licensed GMRS service fills in the United States are, in other countries, filled by unlicensed or class-licensed services. Generally these services have strict technical standards for equipment to prevent interference with licensed transmitters and systems.

In Canada, hand-held GMRS radios up to 2 watts have been approved for use without a license since September 2004.[6] Typically these are dual FRS and GMRS units, with fixed antennas, and operating at 2 watts on some GMRS channels and 0.5 watts on the FRS-only channels. Mobile units (permanently mounted in vehicles), base stations and repeaters are not currently permitted on the GMRS channels in Canada.

Other countries have licensed and unlicensed personal radio services with somewhat similar characteristics, but technical details and operating conditions vary according to national rules. Many European countries use a similar 8 channel system near 446 MHz known as PMR446. GMRS equipment that is approved for use in the United States will not communicate with PMR446 radios, and generally will not be approved for operation in other countries.

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