Reference

On this page, there is a reference to the functions, classes and methods of the PyNGHam library, including a description of each one, and the inputs and outputs.

Main Module

class pyngham.pyngham.PyNGHam(mod=0)

PyNGHam main class.

This class is used to encode and/or decode a NGHam packet.

decode(pkt)

Decodes a NGHam packet.

Parameters:: pkt (list[int], bytearray or str) – raw NGHam packet to decode.
Returns:: The decoded data, the number of corrected errors and a list with the bit position of the errors.
Return type:: list[int], int, list[int]

decode_byte(byte)

Decodes a single byte from a NGHam packet.

This function returns the decoded packet when the complete sequence of bytes is received.

Parameters:: byte (int) – byte of a raw NGHam packet to decode.
Returns:: The decoded data, the number of corrected errors and a list with the bit position of the errors (empty data if the decoding process is not done).
Type:: list[int], int, list[int]

encode(pl, flags=0)

Encodes a sequence of bytes as a NGHam packet.

Parameters:

pl (list[int], bytearray or str) – Data to encode as a NGHam packet (list of integeres, byte array or string).
flags (int, optional) – Packet flags, default 0.

Returns:

An encoded NGHam packet.

Return type:

list[int]

class pyngham.pyngham.State(value)

Decoder states:

SIZE_TAG
SIZE_TAG_2
SIZE_TAG_3
SIZE_KNOWN
STATUS
STATUS_2

SPP Module

class pyngham.spp.PyNGHamSPP

The protocol is used to transfer data and commands between the transceiver and the serial port host.

decode(pkt)

Decodes an SPP packet.

Parameters:: pkt – is the SPP packet to decode.
Returns:: The decoded packet as a dictionary.
Return type:: dict

decode_byte(c)

Decodes a single byte from a SPP packet.

Parameters:: c (int) – is the byte from a SPP packet to decode.
Returns:: An empty dictionary while the decoding is not done yet, and a dictionay with the decoded data when the decoding is ready.
Return type:: dict

encode(pkt_type, pl)

Encodes a generic SPP packet from a given payload data. The SPP packets have the following fields:

Name	Size (Byte)	Notes
Start tag	1	Fixed as ’$’.
CRC Size	2	16-bit CRC CCITT (start=0xffff, polynomial=0x1021 reversed, Xorout=0xffff). Notice the use of little endian, as everything on this layer and up use little endian. CRC is calculated of everything except start tag and CRC itself.
Payload type	1	0x00=RF receive packet, 0x01=RF transmit packet, 0x02=Local packet, 0x03=Command.
Payload length	1	Length of payload field.
Payload	n	This is the actual payload specified by the payload type.

Parameters:

pkt_type (int) – The SPP packet type (SPPType.RX.value, SPPType.TX.value, SPPType.LOCAL.value or SPPType.CMD.value).
pl (list[int]) – The payload of the desired SPP packet.

Returns:

The encoded SPP packet.

Return type:

list[int]

encode_cmd_pkt(cmd)

Encodes a command packet.

This type of packet is used to enter commands. On the Owl VHF, this command will do the same as typing into the command-line interpreter, except the commands and replies are not terminated by LF/CR/CRLF. The table below describes what is put into the payload of the general packet format.

Name	Size (Byte)	Notes
Command	n B	Non-terminated command, 144800000”.

Parameters:: cmd (int) – A list with command content of the packet.
Returns:: The encoded SPP command packet.
Return type:: list[int]

encode_local_pkt(flags, data)

Encodes a local packet.

Packet generated by the radio (not received over the air). For example a status report. The table below describes what is put into the payload of the general packet format.

Name	Size (Byte)	Notes
Flags	1	Bit 0: NGHam extension enabled flag.
Data	n-1 B	Data to be transmitted.

Parameters:

flags (int) – Local packet flags (see table above).
data (list[int]) – The data of the local packet.

Returns:

The encoded SPP local packet.

Return type:

list[int]

encode_rx_pkt(noise_floor, rssi, symbol_errors, flags, data)

Encodes an RX packet from the given data.

Data received from RF link. Length from 4 to 223. The table below describes what is put into the payload of the general packet format.

Name	Size	Notes
Time of hour in microseconds	4	Local time of hour timestamp of the incoming packet. Wraps from 3599999999 (one step before 3600 seconds) to 0. N/A-value is 0xffffffff.
Noise floor	1	Subtract 200 to get dBm. Eg. 0x50 = -120 dBm. N/A is 0xff.
RSSI	1	Same as above.
Symbol errors	1	Number of corrected Reed-Solomon symbols.
Flags	1	Bit 0: NGHam extension enabled. If this bit is set, the data field is a valid NGHam extension packet.
Data	n-8	Received data.

Parameters:

noise_floor (int) – Noise floor value (see table above).
rssi (int) – RSSI value (see table above).
symbol_errors (int) – The number of corrected Reed-Solomon symbols.
flags (int) – RX packet flags (see table above).
data (list[int]) – The data of the packet.

Returns:

The encoded SPP RX packet.

Return type:

list[int]

encode_tx_pkt(flags, data)

Encodes a TX packet from the given data.

Data to be transmitted on RF link. Length from 1 to 220. The table below describes what is put into the payload of the general packet format.

Name	Size (Byte)	Notes
Flags	1	Bit 0: NGHam extension enabled flag.
Data	n-1 B	Data to be transmitted.

Parameters:

flags (int) – TX paket flags (see table above).
data (list[int]) – The data of the packet.

Returns:

The encoded SPP TX packet.

Return type:

list[int]

class pyngham.spp.SPPState(value)

States:

START: Decoder in start flag field
HEADER: Decoder in header field
PAYLOAD: Decoder in payload field

class pyngham.spp.SPPType(value)

Serial Port Protocol packets types:

RX: RF RX packet
TX: RF TX packet
LOCAL: Local packet
CMD: Command packet

Extension Module

class pyngham.extension.ExtPktType(value)

Extension packets types.

DATA: Generic data packet
ID: ID packet
STAT: Status packet
SIMPLEDIGI: Simple digi packet
POS: Position data packet
TOH: Time info packet
DEST: Destination/receiver callsign
CMD_REQ: Command request packet
CMD_REPLY: Command reply packet
REQUEST: Request packet

class pyngham.extension.PyNGHamExtension

Class to handle NGHam extension packets.

append_dest_pkt(pl, call_ssid)

Adds a destination extension packet to a NGHam payload.

Parameters:

pl (list[int]) – is the packet payload to append a destination packet.
call_ssid (list[int]) – 7 x 6 bit (SIXBIT DEC, which is ASCII-32 and limited to 0-64) empty characters padded with 0, 6 bit SSID.

Returns:

The given payload with the new destination extension packet.

Return type:

list[int]

append_id_pkt(pl, call_ssid, sequence)

Adds a ID extension packet to a NGHam payload.

Note:

Always first in a packet, except when resent by another station.

Parameters:

pl (list[int]) – is the packet payload to append an ID packet.
call_ssid (list[int]) – 7 x 6 bit (SIXBIT DEC, which is ASCII-32 and limited to 0-64) empty characters padded with 0, 6 bit SSID.
sequence (int) – is the packet sequence number, wraps around from 255 to 0.

Returns:

The given payload with the new ID extension packet.

Return type:

list[int]

append_pkt(pl, typ, data)

Appends a new extension packet to a NGHam payload.

Parameters:

pl (list[int]) – is the packet payload to append an extension packet.
typ (int) – is the type of extension packet.
data (list[int]) – is the content of the extension packet.

Returns:

The given payload with the extension packet.

append_pos_pkt(pl, latitude, longitude, altitude, sog, cog, hdop)

Adds a position extension packet to a NGHam payload.

Parameters:

pl (list[int]) – is the packet payload to append a position packet.
latitude (int) – Latitude in degrees * 10^7
longitude (int) – Longitude in degrees * 10^7
altitude (int) – Altitude in centimeters
sog (int) – Hundreds of meters per second
cog (int) – Tenths of degrees
hdop (int) – In tenths

Returns:

The given payload with the new position extension packet.

Return type:

list[int]

append_stat_pkt(pl, hw_ver, serial, sw_ver, uptime_s, voltage, temp, signal, noise, cntr_rx_ok, cntr_rx_fix, cntr_rx_err, cntr_tx)

Adds an statistic extension packet to a NGHam payload.

Parameters:

pl (list[int]) – is the packet payload to append an statistic packet.
hw_ver (int) – hardware version ID (10b for company, 6b for product).
serial (int) – Serial number.
sw_ver (int) – software version ID (4b major, 4b minor, 8b build).
uptime_s (int) – time in whole seconds since startup.
voltage (int) – input voltage in decivolts (0-25.5)
temp (int) – system temperature in degrees Celsius (-128 to 127).
signal (int) – received signal strength in dBm - 200, -200 to 54 (0xFF=N/A).
noise (int) – noise floor, same as above.
cntr_rx_ok (int) – packets successfully received.
cntr_rx_fix (int) – packets with corrected errors.
cntr_rx_err (int) – packets with uncorrectable errors.
cntr_tx (int) – packets sent.

Returns:

The given payload with the new statistic extension packet.

Return type:

list[int]

append_toh_pkt(pl, toh_us, toh_val)

Adds a TOH extension packet to a NGHam payload.

Parameters:

packet (pl is the packet payload to append a TOH) –
toh_us (int) – time of hour in microseconds.
toh_val (int) – validity.

Returns:

The given payload with the new TOH extension packet.

Return type:

list[int]

decode(pl)

Decodes all extension packets in a given NGHam payload.

Parameters:: pl (list[int]) – is the NGHam payload to decode.
Returns:: All found extension packets as a list of dictionaries.
Return type:: dict

decode_callsign(enc_callsign)

Decodes a given encoded callsign.

Parameters:: enc_callsign (list[int]) – the encoded callsign to decode.
Returns:: The decoded callsign as an string.
Return type:: str

encode_callsign(callsign, ssid)

Encodes a given callsign.

Parameters:

callsign (str) – is the callsign to encode (ASCII string).
ssid (int) – is the SSID to encode with the callsign (integer).

Returns:

The encoded callsign as a list of integers (bytes).

Return type:

list[int]

get_numpkts(d)

Gets the number of extension packets in a NGHam packet.

Parameters:: d (list[int]) – is the packet payload with extension packet(s).
Returns:: The detected number of extension packets.
Return type:: int