4.0 E
XTENDED
R
ADIO
P
ACKET
M
ODEM
F
EATURES
4.1 T
HROUGH
P
UT
The RPM3B supports three rates, max (17kbps), slots (3.6kbps) and slotsw (1.8bps), of over-air throughput.
M
AX
: When set to maximum and streaming data at the RPM3B, the data is sent as quick as possible.
For host baud rates above 9600bps, data is transmitted continuously with minimal delay between
sequential packets. When this occurs, there is effectively no airtime for another pair, operating in close
proximity, to transmit without causing collisions. The maximum over-air throughput that can be
achieved is 17kbps with ACK and 28kbps without ACK..
Figure 8: RPM3B streaming data
with ACK at maximum throughput
In Figure 8, RS232 serial data bytes accumulated in the receive buffer is transmitted as two 10kbps bursts by
transmitting RPM3B with gaps just enough to receive ACK from receiving RPM3B.
Figure
9: RPM3B streaming data
without gap for anotherRPM3B pair
For continuous data transmission at baud rates above 9600bps (with ACK) or 19200bps (without ACK),
hardware flow control should be used to prevent the host from causing receive buffer overrun errors. RPM3B
will signal CTS pin to stop/allow the host depending on its Receiver Buffer level.
Radiometrix Ltd.
UHF FM Radio Packet Modem
page 10
RADIOMETRIX [ RADIOMETRIX LTD ]
