Not included are the five dedicated R / C frequencies 26.995 MHz, 27.045 MHz, 27.095 MHz, 27.145 MHz, 27.195 MHz and the shared R / C and CB voice frequency of Channel 23 27.255 MHz.
22.
At the rate of 45.45 ( ?.5 % ) baud considered speedy at the time up to 25 telex channels could share a single long-distance telephone channel by using " voice frequency telegraphy Western Union telegram circa 1930
23.
The R Type system was limited to four duo-directional channels using a frequency between 3300 and 5220 cycles per second, which was above normal voice frequency but below the range of other established carrier systems, which used high frequency bands.
24.
Where the internet connection is via a Voice frequency modem ( I still have one, it runs at a maximum of 56kb so I don't use it ! ), only one of the three can be used at any one time.
25.
At the rate of 45.45 ( ?.5 % ) baud considered speedy at the time up to 25 telex channels could share a single long-distance telephone channel by using " voice frequency telegraphy multiplexing ", making telex the least expensive method of reliable long-distance communication.
26.
To implement the system, the army contracted Bell Laboratories and they developed a system called SIGSALY . With SIGSALY, ten channels were used to sample the voice frequency spectrum from 250 Hz to 3 kHz and two channels were allocated to sample voice pitch and background hiss.
27.
Loading coils inserted periodically in series with a pair of wires reduce the attenuation at the higher voice frequencies up to the cutoff frequency of the low-pass filter formed by the inductance of the coils ( plus the distributed inductance of the wires ) and the distributed capacitance between the wires.
28.
An R Type Carrier System, developed in Australia during World War II to cater for pockets of telecommunications traffic congestion, particularly in places where a telephone carrier was not available to supply a channel for a voice frequency system, was installed along the old overland telegraph route from Mount Surprise to Cape York.
29.
For example, if a given radio signal comes from a radio used in a tank, if the interceptor does not hear engine noise or higher voice frequency than the voice modulation usually uses, even though the voice conversation is meaningful, MASINT might suggest it is a deception, not coming from a real tank.
30.
Matching is a much more critical requirement at RF than it is at voice frequencies, so when cable started to become available that was truly 50 ? a need arose for matching circuits to interface between the new cables and legacy equipment, such as the rather strange 51.5 ? to 50 ? matching network.
