Spectra Precision ProMark 800 Reference Manual - Manual (Page 88)

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RTK Implementation
• UHF Frequency band: Range of UHF frequencies on
which the radio transmits or receives data (license-free
radios operate in the 850-930 MHz band, other radios in
the 410-470 MHz band).
• Channel spacing or channel bandwidth: Space occupied
by one channel (in kHz).
• Radiated power: Transmission power, in watts (W) radiated
by the radio used at the base.
• Channel number: Corresponds to a specific carrier
frequency within the band. In theory, the number of
available channels is equal to the ratio between the whole
frequency band and the one-channel bandwidth.
• Modulation type: A parameter that defines the technique
used to modulate the carrier with RTK correction data
(GMSK or FSK)
• Radio data rate: Speed at which the carrier frequency is
modulated with RTK correction data. Expressed in kbits/
second. Not to be confused with the baud rate of the serial
line connecting the radio to the rest of the equipment.
• Frequency hopping (or Spread Spectrum): A process
through which the radio regularly changes the carrier
frequency. The radio usually loops on several preset
channel numbers. In some countries, regulations exist
that require the implementation of this technique.
• Duty Cycle: Ratio between the time period a radio is on
(i.e. is transmitting) and a full cycle of radio on/off
periods. In some countries, regulations exist to maintain
this parameter under a certain threshold.
• Operation indicator: The ability for a radio to inform users
in real time of the quality and strength of the signal
transmitted or received.
• Forward Correction Error (FEC): Made available by some
radio manufacturers. A function or process through which
a radio system gives itself the capability to correct the
data bits that are corrupted during the radio transmission.
This process is based on the use of additional bits
encoded at transmitter level, calculated from the real data
bits that have to be transmitted. At receiver level, the bit
streams are analyzed. Isolated bits may be found
corrupted in which case they are brought back to their real
value (1 instead of 0 or the other round). This process
involves interleave techniques on both sides of the radio
transmission.