MChGJ-0800

The MChGJ-0800 (Menghean abbr. for 무전기, 초고주파 / 無電機,超高周波, Mujŏn'gi, Chogojupa, "Radio, super-high frequency is a family of radio systems used on land vehicles of the Menghean Army. It transmits in the C-band and is used for short-range communication between land vehicles, without the use of a satellite relay.

Because signals in the C-band do not diffract around obstacles, MChGJ-0800 family radios are limited to line-of-sight communication. This limits their effectiveness to communication between individual vehicles in a battery, company, or platoon. By virtue of the same limitations, however, it is also much more resistant to jamming and interception than UHF and VHF antennas, and allows the same frequency to be reused at shorter intervals along the front line.

Characteristics

All radios in the MChGJ-0800 family transmit in the C-band of radio frequencies, which is part of the wider SHF range. This frequency brings a unique series of advantages and disadvantages. The main disadvantage is the lack of groundwave effects: SHF signals do not diffract around the surface of the earth, or around obstacles on the ground. This means that the system can only be used when the transmitting and receiving antennas are linked by direct line-of-sight.

An advantage of this characteristic, however, is that C-band transmissions cannot be intercepted or jammed unless the enemy's electronic-warfare units have direct line-of-sight contact with the transmitter as well. The high bandwidth of the SHF band also allows high-volume data transfers and more extensive use of pseudorandom frequency hopping, further improving resistance against electronic warfare.

SHF frequencies are also low enough that they do not suffer high atmospheric attenuation, even under conditions of rain, fog, or snow. This makes the system capable of operating in the humid subtropical climate of the Menghean-Maverican border, which experiences torrential rain during the summer monsoon season. Concern over attenuation in adverse weather is what led the Menghean Ministry of Defense to choose SHF over EHF frequencies.

Use

Menghean brochures on the MChGJ-0800 series, including those published by the Gunsu International arms export corporation, note that it is intended as a complement to VHF and UHF antennas, rather than a replacement for them. Under normal conditions, tank units would communicate using these options, which have superior diffraction characteristics and can function over a longer range.

Under certain adverse conditions, however, vehicle crews would be able to use MChGJ-0800 radio frequencies to communicate securely. This might be done in a unit maintaining emissions control, such as an armored column is preparing for a surprise offensive, or under conditions of intense electronic warfare, in which UHF and VHF frequencies are subject to jamming and interception. Alternatively, vehicle crews in the same platoon may communicate over the C-band antenna to avoid clogging company or battalion radio nets.

Some defense analysts have compared the MChGJ-0800 radio family to semaphore flags, which Menghean tank crews had previously carried since at least 1964 as a backup measure against radio jamming or the loss of signal vehicles. Like semaphore flags, the MChGJ-0800 radios are limited to line-of-sight communications, and are thus no worse than their predecessor. Unlike semaphore flags, however, the MChGJ-0800 can transmit voice signals and targeting information at a higher rate, and does not require either tank commander to expose himself to atmospheric contaminants or small-arms fire. It also allows tank commanders to send and receive messages without distracting them from their tasks of searching for targets and maintaining situational awareness.

Use of the MChGJ-0802 variant is somewhat different; this system has a higher bandwidth with reduced frequency hopping, and is able to transmit larger volumes of data. It may be used for within-battery data-sharing in surface-to-air missile systems, land-launched anti-ship missile systems, and long-range multiple rocket launcher systems, allowing launch vehicles to receive targeting information from the battery command post or radar. As with the -0801, it is more secure than VHF and UHF communications, but is faster to deploy than direct telephone wire connections between battery vehicles, which slow the transition time between ready status and a road march and are vulnerable to being driven over.

Variants

• MChGJ-0801: Basic variant used on tanks and infantry fighting vehicles. Primarily restricted to voice communications, but has limited datalink capabilities, allowing tanks to designate target locations to one another.
• MChGJ-0802: More powerful variant mainly used on networked supporting weapons.
• MChGJ-0803: Lightweight but even shorter-range handheld variant issued to ground troops beginning in September 2016. Allows infantry to communicate with tank crew in combined-arms combat, a superior alternative to tank-mounted telephone units.
• MChGJ-0810: Series of similar radio units (0811, 0812, 0813) which use a different pseudorandom frequency-hopping system from that in Menghean radio units. Sold for export by Gunsu International.

Specifications (MChGJ-0801)

• Type: omnidirectional
• Height (antenna casing): 410 mm
• Diameter (antenna casing): 45 mm
• Frequency: 4.40 - 5.00 GHz
• Gain: 5 dBi
• Beamwidth, azimuth: 360°
• Beamwidth, elevation: 24°
• Max power input: 5 W
• Operational temperature range: -40°C to +80°C