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TCP Message Header Structure

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Field	Type [Size]	Description
Signature	uint8_t [16]	Unique synchronisation byte sequence
Version	uint8_t [1]	Protocol version – indicates the revision of the protocol messages
Message Id	uint8_t [1]	Message type – indicates the type of the payload
Payload Size	uint32_t [4]	The size, in bytes, of the main body of the message

TCP Message Types

Message Name	Message Id	Direction	Description
Keep Alive	1	From Radar	An empty payload message to confirm client connection
Configuration	10	From Radar	Sends all the radar configuration properties required to configure the client software to correctly receive data
Configuration Request	20	To Radar	Requests a configuration message from the radar
Start FFT Data	21	To Radar	Instructs the radar to start sending FFT data until told to stop
Stop FFT Data	22	To Radar	Instructs the radar to stop sending FFT data
Start Health Msgs	23	To Radar	Instructs the radar to start sending regular health messages until told to stop
Stop Health Msgs	24	To Radar	Instructs the radar to stop sending health messages
Reset RF Health	25	To Radar	Instructs the radar to reset RF Health check system
FFT Data	30	From Radar	An azimuth of raw radar data
High Precision FFT Data	31	From Radar	An azimuth of high precision radar data
Health	40	From Radar	Sends a radar health status message
Contour Update	50	To Radar	Enables the client to update the contour map on the radar
Sector Blanking Update	51	To Radar	Updates the blanking sectors on the radar
System Restart	76	To Radar	Request system reboot
Logging Levels	90	To/From Radar	A list of logging levels - v2 Hardware only
Logging Levels Request	100	To Radar	Request a list of logging levels - v2 Hardware only
Start Nav Data	120	To Radar	Request system to start sending navigation data
Stop Nav Data	121	To Radar	Request system to stop sending navigation data
Set Nav Threshold	122	To Radar	Set navigation threshold
Navigation Data	123	From Radar	Navigation data records
Set Nav Range Gain and Offset	124	To Radar	Set navigation threshold
Calibrate Accelerometer	125	To Radar	Radar will store current accelerometer value as float
Start Accelerometer	126	To Radar	Start receiving accelerometer data
Stop Accelerometer	127	To Radar	Stop receiving accelerometer data
Accelerometer Data	128	From Radar	Accelerometer Data
Navigation Alarm Data	143	From Radar	SafeGuard Lite Alarms
Navigation Area Rules	144	To Radar	SafeGuard Lite Area Rules
Navigation Configuration Request	203	To Radar	Request the current navigation configuration from the Radar
Navigation Configuration	204	From Radar	The current navigation configuration
Set Navigation Configuration	205	To Radar	Updates the Radar’s navigation configuration
Request Navigation Area Rules	206	To Radar	Request the current Navigation Area Rules
Request Time Server Status	207	To Radar	Request the current status of time server sources
Time Server Status	208	From Radar	NTP and/or PTP time server status
Start Radar	209	To Radar	Start radar rotation and transmitter
Stop Radar	210	To Radar	Stop radar transmitter and rotation

Signature

The 16 byte signature differs very slightly from the older Navtech RMB protocol. This does enable existing software to differentiate between the two protocols if required.

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Configuration Message Structure

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Field	Type [Size]	Description
Azimuth Samples	uint16_t [2]	Number of azimuth samples taken per rotation
Bin Size / Resolution	uint16_t [2]	The range resolution per bin. In tenths of millimetres. For example 0.2997m would be 2997.
Range In Bins	uint16_t [2]	Configured detection range, in bins
Encoder Size	uint16_t [2]	The total number of available steps on the encoder wheel
Rotation Speed	uint16_t [2]	The configured rotation speed for the radar. In milliHertz i.e. 2000 = 2 Hz
Packet Rate	uint16_t [2]	Expected packet rate based on sample time and rotation speed
Range Gain	float [4]	Gain applied to calculated ranges based on radar calibration
Range Offset	float [4]	Fixed offset in metres, applied to calculated ranges based on radar calibration

Floats transmitted over the network are IEEE 754 compatible values converted to 32 bit unsigned integers in network order. They will need to be reverted to host order and then cast back to floats on the client.

In C++ the radar converts floats using the following code snippet:

Code Block
union v { float f; uint32_t i; }; v value; value.f = 186.4f; uint32_t networkData = htonl(value.i);

Configuration Protocol Buffer Payload

FIeld	Type [Size]	Description
Model	string	Customer friendly model name
MAC Address	string	Networking MAC Address
Service Date	uint32_t [4]	The date the last service was completed
Software Version Numbers	SoftwareVersion PB Message	Collection of software version numbers
NVRAM Contents	NVRAM PB Message	Contents of NVRAM, including radar serial number
Range Resolution Hz	float	Resolution of each bin in Hz
Module Serial Number	string	Processing Module Serial Number
Auto Tune Value	int16_t [2]	Current Auto Tune Value
Radar Unique Id	string (Guid)	Radar's Unique Id
Data Width	int32	1 for 8-bit 2 for 16-bit
Range Resolution Metres	float	Range of each bin in metres
Radar Feature Flag	uint32	Feature Flag bit field 1 = AutoTune, 2 = Secondary Processing Module Present
Staring Mode	int32	Boolean to represent staring mode enabled on radar
On-Board MAC Address	string	On-Board Networking MAC Address - 00:00:00:00:00:00 indicates no module

Info

Converting Bins to Range (m)

This information can be used to calculate the range of the radar in metres and also when receiving FFT data the range of each bin can be calculated. The following algorithm should be used:

Range = Range In Bins * Range Resolution (m) i.e. 3768 * 0.175 = 659.4 m (This radar has a total range of 659.4 m)

Range of single bin = Bin Number * Range Resolution (m) i.e. 100 * 0.175 = 17.5 m (Bin 100 is 17.5 m from the radar)

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Set Navigation Threshold Message Structure

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Field	Type [Size]	Description
Threshold	uint16_t [2]	Threshold to use for navigation data. This should be a value between 0 - 96.5 dB multiplied by 10 e.g 75.6dB is 756

Set Navigation Gain and Offset

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Set Navigation Gain and Offset Message Structure

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Field	Type [Size]	Description
Gain	uint32_t [4]	Gain multiplied by 1000000
Offset	uint32_t [4]	Offset multiplied by 1000000

FFT/High Precision Data Message

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FFT/High Precision Data Message Structure

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Field	Type [Size]	Description
FFT Data Offset	uint16_t [2]	The offset from the start of the payload where the FTT data starts. In this version the value will be 14 – the FFT starts at the 15th byte
Sweep Counter	uint16_t [2]	A counter that increments on each packet sent from the radar. The value will rollover once the maximum type size has been reached
Azimuth	uint16_t [2]	The azimuth at which this sample of FFT data was taken
Seconds	uint32_t [4]	Total number of seconds since the synchronised Epoch (In little Endian order)
Split Seconds	uint32_t [4]	Part seconds. This value rolls over each second (In little Endian order)
FFT Data	uint8_t [n]	Variable length byte array of amplitude data per range bin (If high precision then two bytes represent one bin)

Info

Azimuth to Bearing Algorithm

To convert from an azimuth to bearing you can use the following algorithm, utilising information from the configuration message:

Bearing = (Azimuth / Encoder Size) * 360 e.g. (2800 / 5600) * 360 = 180°

This bearing is relative to the Zero/North point of the radar, for CDR/CIR radars this is a line perpendicular to the flat part of the base:

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Navigation Data Message Structure

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Field	Type [Size]	Description
Azimuth	uint16_t [2]	The azimuth at which this sample of data was taken
Seconds	uint32_t [4]	Total number of seconds since the synchronised Epoch
Split Seconds	uint32_t [4]	Part seconds. This value rolls over each second
Navigation Data Pairs	uint8_t [n]	Pairs of ranges and powers representing targets

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Field	Type [Size]	Description
Range	uint32_t [4]	Range in metres multiplied by 1000000
Power	uint16_t [2]	Power of target dB multiplied by 10 e.g 75.6dB is 756

Health Message

The health message includes critical health information about the radar. The payload consists of a number of health status structures, each one provides data on a specific metric, for example temperature, and includes details on the current measurement and whether the metric is within expected bounds or not. The health message payload is a Protocol Buffer serialised byte array. In order to de-serialise the message the client will need to use the Google library as described in reference [2]. Metrics may be added or changed within the content of the Protocol Buffer message. This would not result in a new protocol version for this message. Client applications consuming this message will need the latest Protobuf definition file from Navtech. These are available on request. Health messages need to be switched on before they are transmitted. Once active, health messages will be sent every 5 seconds. Messages will continue to be sent until the radar receives a message to stop. Clients should honour this mechanism and, where possible, send the radar a stop message before disconnecting.

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Health message Protocol Buffer structure

Field	Type [Size]	Description
Die temperature	HealthInfo PB Message	Die temperature
SOC temperature	HealthInfo PB Message	System On Chip temperature
VCO temperature	HealthInfo PB Message	Voltage Controlled Oscillator temperature
Ambient temperature	HealthInfo PB Message	Radar-measured ambient temperature
Rotation	HealthInfo PB Message	Current speed
Packet Rate	HealthInfo PB Message	Current packet rate
RF Health Check	HealthInfo PB Message	RF health information
Transmitting	bool	Transmitter enabled
Expected rotation	uint32	Expected radar rotation speed in mHz
Expected packet rate	uint32	Expected data output rate in packets/sec
MAC address	string	Radar MAC address
Encoder error count	int32	Errors recorded from the radar rotary position encoder
System uptime	float	Seconds since last reboot
Motor Current	HealthInfo PB Message	Motor current draw
Software uptime	uint64	Seconds the firmware has been running
Total uptime	uint64	Cumulative time the system has been operating for
Network state	NetworkInfo PB mesage	Network information
Client limit	int32	The maximum number of clients allowed
IP clients	string	IP addresses of any currently-connected clients
Expected RX packet rate	uint32	Expected receive packet rate, based on current configuration, in packets/sec
Uplink errors	uint32	Internal link uplink error count
Downlink errors	uint32	Internal link downlink error count
Uplink missed	uint32	Internal link uplinks missed error count
Downlink missed	uint32	Internal link downlinks missed error count
Running uptime	uint64	Number of seconds the radar has been rotating

HealthInfo Protocol Buffer structure

Field	Type [Size]	Description
Minimum value	float	Lower bound
Maximum value	float	Upper bound
Value	float	Current value
Status	Enumeration	Current health status - HEALTHY, WARNING, UNHEALTHY, UNKNOWN
Warning allowance	int32	The number of out-of-bounds samples before the health status transitions from HEALTHY to WARNING
Unhealthy allowance	int32	The number of out-of-bounds samples before the health status transitions from WARNING to UNHEALTHY
Clear allowance	int32	The number of in-bound samples before the health status returns to HEALTHY

NetworkInfo structure

Field	Type [Size]	Description
Network state	Enumeration	Current network state - UP, DOWN or UNKNOWN
Duplex	Enumeration	Network duplex - HALF or FULL
Speed	uint32	Network speed

Contour Update Message

The Contour Update message controls the contour mode and contour map. The contour map is held on the radar and provides a mechanism to restrict the radar detection area. The map consists of a variable range per degree (i.e. 360). When a contour map is active, data is sent out from the radar for each degree up to the range specified. If the range is zero then no data is sent for that bearing. If the contour map is disabled or in its default configuration then the full range of data is sent for every azimuth (i.e. all data). There is also a test mode which can be set on the radar – this activates a pre-configured map which exhibits a distinctive data pattern. To disable the contour map the client should send an empty update message (just header). This will leave the contour configuration intact but tell the radar to stop using it. Alternatively the client can send a full contour map, in other words a maximum range value for each azimuth. This will have the same effect. The contour map, once active, restricts the amount of data sent over the network. The more restrictive the contour map, the less data that is sent.

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Log Levels Buffer Payload

Field	Type [Size]	Description
Items	List of LogLevel PB Messages	A list of Log Level Items

Calibrate Accelerometer Message

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Accelerometer Data Message Structure

Field	Type [Size]	Description
Θ (theta)	float [4]	Angle around axis running perpendicular to zero/north - +ve Tilted Forward, -ve Tilted Backward
Ψ (psi)	float [4]	Angle around axis running from base to stop of radome
ɸ (phi)	float [4]	Angle around axis running through radar zero/north - +ve Tilted Right, -ve Tilted Left

Navigation Alarm Data

This messages contains the six alarm states of the SafeGuard Lite feature

Field	Type [Size]	Description
Alarm States	uint8_t[6]	Each byte represents the alarm state of an areas so state[4] is the fifth alarms sate a value of 1 means alarm in area, 0 means no alarm

Navigation Area Rules Get/Set Messages

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A Navigation Area Rules message is a variable length message, consisting of one or more Navigation Area Rule structures.

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Field	Type [Size]	Description
Rule count	uint8_t [1]	The number of rules in the message; should not be zero
Enable health	bool [1]	Enables health status output. If set, navigation area 6 is ignored and its output is used to indicate overall system health.
Failsafe mode	bool [1]	Enable fail-safe mode for relay output.
Navigation Area Rules	Navigation Area Rule[Payload Size -

1

3]	A contiguous sequence of up to 6 Navigation Area Rules

A Navigation Area Rule consists of a fixed header, plus a variable number of Points, which define the area over which the rule is applied.

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Field	Type [Size]	Description
Rule Length	uint32_t [4]	The complete size of the Rule in bytes. This value is calculated as sizeof (rule header) + (point count * sizeof(Point))
ID	uint8_t [1]	Integer identifier
Enabled	bool [1]	uint8_t interpreted as an implied Boolean: 0 - false; 1 - true
Invert break logic	bool [1]	uint8_t interpreted as an implied Boolean: 0 - false; 1 - true
Threshold delta	float [2]	Floating point value, stored as a signed 2-byte integer to one (implied) decimal place. That is, the stored value is held as (actual value * 10.0)
Break allowance	uint16_t [2]	Break allowance as 16-bit unsigned value
Allowance curve decrement	uint16_t [2]	Allowance curve decrement as 16-bit unsigned value
Point count	uint16_t [2]	The number of Point objects that follow for this Rule
Points	Point [point count * sizeof(Point)]	A variable number of Point structures, stored contiguously

A Point is a fixed-size structure, holding coordinates. A Navigation Area Rule will contain a variable number of points, defining an area.

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Field	Type [Size]	Description
x	float [2]	Floating point value, stored as a signed 2-byte integer to one (implied) decimal place. That is, the stored value is held as (actual value * 10.0)
y	float [2]	Floating point value, stored as a signed 2-byte integer to one (implied) decimal place. That is, the stored value is held as (actual value * 10.0)

C# Example of how to encode rules

Code Block

public static class Utility
{
    public static uint SwapUInt32(uint value)
    {
        return (uint)((SwapUInt16((ushort)((value & 0x000ffff))) << 0x10)) | (SwapUInt16((ushort)((value >> 0x10) & 0xffff)));
    }
 
    public static ushort SwapUInt16(ushort value)
    {
        return (ushort)(((value & 0xff) << 8) | ((value >> 8) & 0xff));
    }
}
 
public class NavVector
{
    public NavVector() { }
 
    public NavVector(float x, float y)
    {
        X = x;
        Y = y;
    }
 
    public float X { get; set; }
    public float Y { get; set; }
 
    public byte[] ToBytes()
    {
        var x = (short)(X * 10.0f);
        var y = (short)(Y * 10.0f);
        var data = (uint)(x << 16) | (uint)y;
        return BitConverter.GetBytes(Utility.SwapUInt32(data));
    }
}
 
public class NavArea
{
    public NavArea()
    {
        Points = new List<NavVector>();
    }
 
    public List<NavVector> Points { get; set; }
 
    public byte[] ToBytes()
    {
        var data = new List<byte>();
        data.AddRange(BitConverter.GetBytes(Utility.SwapUInt16((ushort)Points.Count)));
        Points.ForEach(point => { data.AddRange(point.ToBytes()); });
        return data.ToArray();
    }
}
 
public class NavAreaRule
{
    public NavAreaRule()
    {
        Enabled = true;
        InvertBreakLogic = false;
        ThresholdDelta = 0.0f;
        BreakAllowance = 16;
        AllowanceCurveDecrement = 4;
        AreaToCheck = new NavArea();
    }
 
    public byte Id { get; set; }
    public bool Enabled { get; set; }
    public bool InvertBreakLogic { get; set; }
    public float ThresholdDelta { get; set; }
    public ushort BreakAllowance { get; set; }
    public ushort AllowanceCurveDecrement { get; set; }
    public NavArea AreaToCheck { get; set; }
 
    public byte[] ToBytes()
    {
        var ruleData = new List<byte> { Id, Enabled ? (byte)1 : (byte)0, InvertBreakLogic ? (byte)1 : (byte)0 };
        ruleData.AddRange(BitConverter.GetBytes(Utility.SwapUInt16((ushort)(ThresholdDelta * 10.0f))));
        ruleData.AddRange(BitConverter.GetBytes(Utility.SwapUInt16(BreakAllowance)));
        ruleData.AddRange(BitConverter.GetBytes(Utility.SwapUInt16(AllowanceCurveDecrement)));
        ruleData.AddRange(AreaToCheck.ToBytes());
        var data = new List<byte>();
        data.AddRange(BitConverter.GetBytes(Utility.SwapUInt32((uint)ruleData.Count)));
        data.AddRange(ruleData);
        return data.ToArray();
    }
}
 
public class NavUpdateAreaRules
{
    public NavUpdateAreaRules()
    {
        Rules = new List<NavAreaRule>();
    }
 
    public List<NavAreaRule> Rules { get; set; }
 
    public byte[] ToBytes()
    {
        var data = new List<byte> { (byte)Rules.Count };
        Rules.ForEach(rule => { data.AddRange(rule.ToBytes()); });
        return data.ToArray();
    }
}

Navigation Configuration Get/Set Messages

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Navigation Configuration message structure

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Field	Type [Size]	Description
Bins to operate on	uint16_t [2]	Defines the search window in bins for peak detection.
Minimum bin	uint16_t [2]	The earliest bin for which peak detection will be enabled.
Navigation Threshold	float [4]	The threshold level for target detection. This should be a value between 0 - 96.5 dB multiplied by 10 e.g 75.6dB is 756
Max Peaks Per Azimuth	uint32_t [4]	The maximum number of detection peaks that will be reported. Once the maximum number of peaks have been detected, further peaks will be ignored.

Sector Blanking Message

A Sector Blanking message allows the client to update the set of blanking sectors for the Radar.

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Sector Blanking Message Structure

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Field	Type [Size]	Description
Number of Sectors	uint8_t [1]	Specifies the size of the message payload, as a number of Blanking Sector structures. [0 .. 8]
Blanking Sectors	uint8_t [Payload Size - 1]	Up to 8 Blanking Sector structures, held as a sequence of bytes

Blanking Sector Structure

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Field	Type [Size]	Description
Start Angle	float [4]	The start angle of the sector [0 .. 360.0]
Finish Angle	float [4]	The end angle of the sector [0 .. 360.0]

Time Source Status Get/Set messages

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Time Source Status message structure

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Field	Type [Size]	Description
NTP enabled	bool [1]	Is the NTP service enabled (specifically, does the radar have its NTP remote address configured correctly)
NTP synchronised	bool [1]	Is the time service on the radar synchronised with its time server
NTP remote address	uint8_t[4] [4]	The address of the NTP remote. The address is held as an array of 4 octets, in network order If the NTP server is not enabled the IP address will be set to 0.0.0.0
PTP enabled	bool [1]	Is the PTP service enabled
PTP synchronised	bool [1]	Is the time service on the radar synchronised with its PTP server
PTP remote address	uint8_t[4] [4]	The address of the PTP remote. The address is held as an array of 4 octets, in network order If the PTP server is not enabled the IP address will be set to 0.0.0.0
Time seconds	uint32_t [4]	The radar’s clock time at the point of request. Stored as the number of seconds since the epoch (01 Jan 1970 00:00:00)
Time nanoseconds	uint32_t [4]	The nanosecond component of the radar’s clock time.

Start / Stop radar

The Stop Radar message will disable the radar’s transmitter (if enabled) and stop the radar from rotating.

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Old Version 18

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