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MicroMet Manual Pg. 12

Understanding Communications Statistics (Stat Command)

RXSP Signal Presence – this is the number of times the radio receiver has

detected a radio signal that may have been a signal from the Master

Station, or it may have been radio interference. In close proximity to the

Master Station, the MicroMet will normally detect many thousands of

RXSPs per hour. At meteor range, 150-1000 miles, the MicroMet will most

likely detect a few hundred RXSPs per hour.

SYNC Sync Character Detected – when the receiver detects a signal (RXSP) the

MicroMet begins to watch for a special code in the received data stream

called a Sync character. This Sync character must be received in order to

validate the signal received from the Master Station. Under ideal

conditions, for each reception (RXSP), MicroMet would receive one Sync

or validated reception. Under normal conditions, errors in the received

data caused by radio interference, make the ratio of RXSPs to Syncs

somewhat greater than 1:1. A good ratio in the field is probably around 2

or 3 to 1.

RXERR Receive Errors – if the MicroMet detects the Sync during a reception, it

then continues to receive data until the entire probe is complete. If all goes

well with the reception, and the data stream is complete, then the RXERR

does not increment. A high number of RXERRs indicates poor reception

due to interference.

XMIT Transmit Cycles – this number is incremented each time the MicroMet

turns on its transmitter. Under ideal conditions the MicroMet would

activate it’s transmitter only once for each data message it receives from

the CR10X.

ACK Acknowledgement of Data packet – when the MicroMet transmits a data

message, it hopes to immediately receive an ACK from the Master

Station. If this ACK is received, MicroMet dequeues the data message and

shows a ‘Message Delivered’ advisory on the operator’s console or PC

Terminal. If no ACK is received, the data message remains enqueued,

and the MicroMet will attempt to transmit the data again. MicroMet can

only transmit in response to a ‘probe’ or valid reception, which it receives

from the Master Station.

XMIT Transmit to ACK Ratio – under ideal conditions, the ratio of XMIT to ACK

TO ACK would be 1:1. In the field, a ratio of 2 or 3 to 1 should be considered to be

very good. A ratio in excess of 10 or 20 to 1 should be considered to be

very marginal. If no ACKs are received, no data messages are being

delivered and the site is nonfunctional!

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