However, the frequency programmed into the receiver section is the LOCAL OSCILLATOR (LO) frequency,
not the actual channel frequency.
For unit operating on a channel frequency of 446MHz or higher, the local oscillator is 21.4MHz below the
carrier (so subtract 21.4MHz). AF output will be inverted on higher receive frequency units.
LO RF IF 458.700MHz 21.4MHz 437.3MHz
for RF 446MHz
For units operating on frequencies below 446MHz, the local oscillator is 21.4MHz above the channel.
LO RF IF 434.650MHz 21.4MHz 456.05MHz for RF 446MHz
434.650MHz 21.4MHz
RX Example:
70.1615384615
6.5MHz
INTE = 70-1 = 69 (0x45)
FRAC = (0.1615384615 +1) 524288 = 608980 (0x094AD4) 0x094AD4
FRAC2 = 0x09
FRAC1 = 0x4A
FRAC0 = 0xD4
608980
524288
Freq = 65
6.5 456.0499992MHz 456.050MHz 8.4Hz
When programming the NiM2B, keep in mind that the unit maintains in SRAM the current values of all
programmable values (frequency, band of operation, RF power and frequency offset adjustments values)
and that toggling the PGM pin does NOT erase or corrupt them.
These values are only loaded from EEPROM at cold start power-up (but not when the relevant N_TXE or
N_RXE pins are cycled)
There is one "write all values to EEPROM" command. It is usually necessary to load the relevant current
operating RAM value(s) and THEN issue a suitable command to write the RAM value to EEPROM.
The NiM2B stores Frequency coefficients (for transmit and receive), frequency Offsets, band select and TX
RF Power level constants in internal EPROMs.
ALWAYS REMEMBER THAT THE TRANSMIT AND RECEIVE SECTIONS OF THE NiM2B ARE
INDEPENDANT, AND ARE PROGRAMMED ENTIRELY SEPARATELY.
No command sent to the transmitter will have any effect on the receiver, and vice-versa.
For the NiM2B RX section, power level should always be set to 3
Programming a value or coefficient over the serial bus over-writes the previous value and implements this
change on the PLL immediately, but does not change the EEPROM contents until a relevant "program
EEPROM" command is issued
In general, the most recent stimulus received by the unit will decide the operating frequency.
Whenever a frequency coefficient is programmed into the unit, the frequency will change immediately to this
new value regardless of other modes or operation. This is the simplest and most flexible means of controlling
the unit.
Radiometrix Ltd.,
NiM2B transceiver data sheet
Page 6
RADIOMETRIX [ RADIOMETRIX LTD ]
