Research. P192-S Telemetry radio APPLICATION NOTE

Transcription

1 Research P192-S Telemetry radio APPLICATION NOTE

2 Pi P192-S Telemetry Radio Application Note 2 Pi P192-S Telemetry Radio Application Note

3 Disclaimer Pi Research makes no representation or warranties of any kind whatsoever with respect to the contents hereof and specifically disclaims any implied warranties of merchantability or fitness for any particular purpose. Pi Research shall not be liable for any errors contained herein or for incidental or consequential damages in connection with the furnishing, performance or use of the software, associated hardware, or this written material. Pi Research reserves the right to revise this publication from time to time, and to make changes in the content hereof without obligation to notify any person of such revision or changes. A copy of the Pi Research Terms and Conditions of Sale is available on request, and includes a declaration of the warranty and limitation of liability which apply to all Pi Research products and services. Health and Safety information Under the terms of European and UK Health and Safety Legislation, Pi Research is required to classify any hazardous materials in the products it supplies and to provide relevant safety information to users. Any hazardous materials in Pi products are clearly marked with appropriate symbols. Product Safety Data Sheets relating to these materials are available on request. 3

4 Contents Introduction... 6 Licensing information... 6 Car radio installation... 7 Installing a P192-S radio in a car... 7 Car radio transmit antenna... 8 P192-S as a pit receiver Power supply Pit data loom Diversity receiving function Pit receiver antenna Connecting antennas Configuring the P192-S Radio configuration utility P192-S status LED s Serial Interface Baud rate setting Forward error correction (FEC) Pi Sigma stream optimization Minimisation of the Message Size Transmit buffer CTS (Clear to send) Specifications Connector information Connector details Data connector pin details Pi P192-S Telemetry Radio Application Note

5 Parts numbering Dimensions Declaration of conformity Conditions Of Use FCC Authorisation Contact information

6 Introduction The Pi telemetry system provides reliable data transmission from a car to the pits as the car travels around the track. A P192-S radio in the car transmits the telemetry data and a P192-S radio in the pits receives the transmissions. The received telemetry data is passed to a PC for processing and display. The P192-S radio has no user controls and the setup is carried out by Pi Research. The frequency and transmit power can be programmed via the Pi Programming software with the programming lead connected in line with the radio and to a PC s comm port. Licensing information Before you use the telemetry system you must apply to the appropriate radio licensing authority for the frequency and power setting that you intend to use. 6 Pi P192-S Telemetry Radio Application Note

7 Car radio installation Installing a P192-S radio in a car The P192-S radio needs a power supply between 12 to 30 volts DC. If you are connecting the telemetry system to a Pi System, the radio loom connects battery power to the radio system. If you are building your own wiring loom for the telemetry system refer to the section Connector information. CAUTION: The anti-vibration mounts supplied MUST BE used to mount the radio. The radio will not function correctly, may be damaged, and its warranty will be void if the anti-vibrations mounts are not used. When installing the P192-S radio in a car: the anti-vibration mounts supplied MUST BE used to mount the radio. The radio will not function correctly if the anti-vibration mounts are not used; select a position where the radio will not be in constant contact with water, fuel or oil; make sure that the radio will not be affected by heat soak. Ensure that air can flow over the radio to keep it below 55 C; Insufficient airflow will overheat the transmitter, and the radio will shut down until the temperature drops sufficiently. make sure that the radio is electrically isolated from the chassis and all surrounding parts; ensure connector casing is isolated from all loom connections and the loom screen; try not to place the radio near sources of electrical interference e.g. ignition coils, plug leads, ECMs, alternators and other radio transmitters. 7

8 Data loom When installing the data loom, you should avoid running it next to sources of interference, i.e. ignition coils, plug leads, alternators, fuel pumps and ECMs. If the loom has to run near any of these, then try to avoid parallel runs. Car radio transmit antenna Ground planes The transmit antenna needs a suitable ground plane to operate efficiently. The ground plane is a conductive material placed at the base of the antenna and increases the efficiency of the antenna by reducing the amount of power that is reflected back into the radio module. Generally, the construction and shape of a race car does not allow for a suitable ground plane. To use your telemetry equipment effectively, you may have to make a suitable ground plane. Each antenna comes with an installation kit that includes a piece of self-adhesive copper foil which you can use to make a ground plane. When making a ground plane, you should consider the following points: The antenna should be mounted in a vertical position in the centre of the ground plane and at least 150mm (6 inches) away from any vertical piece of the car or other antenna; The ground plane should be circular and have a radius at least equal to the length of the antenna; The ground plane must not make electrical contact with any part of the vehicle chassis that is likely to conduct, for example, carbon fibre. 8 Pi P192-S Telemetry Radio Application Note

9 Fibre glass body panels To fit the antenna to a fibre glass body panel: 1 Locate a suitable panel, that can be removed easily for access to the antenna loom. 2 As fibre glass is electrically non-conducting, you can stick the copper foil directly to the underside of the panel. 3 Tighten the TNC connector of the antenna, ensuring that it makes electrical contact with the copper foil. 4 Ensure that the copper foil does not make contact with any part of the chassis that is likely to conduct. Antenna Insulating washer TNC bulkhead connector Body panel Insulating layer Insulating washer TNC terminated feed cable Copper foil Locking washer Fixing nut Antenna installation detail 9

10 Carbon fibre chassis panels 1 Locate a suitable panel that can be removed easily for access to the antenna loom. An ideal panel is over the front suspension dampers. 2 Make a bracket from metal or carbon fibre that will hold the antenna vertical. Fix the bracket to the chassis. 3 Stick an insulating layer of tank tape to the underside of the bracket. Make sure that it is of a larger diameter than the copper foil for the ground plane. 4 Stick the copper foil to the underside of the insulating layer. 5 Tighten the TNC connector of the antenna, ensuring that it makes electrical contact with the copper foil. 6 Ensure that the copper foil does not make contact with any part of the chassis that is likely to conduct. 7 Drill a hole in the panel for the antenna to pass through. Antenna feed loom If you are going to use your own antenna feed loom, it should be a high quality coaxial cable, with a stranded inner core. We recommend that you use RG58 50 ohm coaxial cable. For best results, use crimp TNC connectors for both the radio and antenna ends of the feed cable. WARNING: It is important that the TNC connectors of the feed loom do not vibrate against any other conducting surfaces such as Lemo connectors or the chassis floor, as this will result in radio frequency noise and a loss of signal. 10 Pi P192-S Telemetry Radio Application Note

11 P192-S as a pit receiver The P192-S radio can be used in a car as a radio transmitter or in the pit as a radio receiver. The pit car transmitter frequency and the pit receiver frequency must be the same. Refer to the section Configuring the P192-S for information. Power supply Use the power supply provided to run the P192-S in the pit. Pit data loom The pit data loom connects the telemetry pit receiver to your PC. The computer connector is a standard RS232 9-pin D-type connector and should be connected to a serial port of your PC. If your PC has more than one serial port, then refer to the documentation that came with your PC to find out how the serial ports are labelled. You can only connect the telemetry data loom to either serial port COM1 or COM2 of your PC. You must use Pi Workshop software to set which ports of your computer are used for telemetry, before you attempt to use the telemetry system. 11

12 Diversity receiving function Where line-of-sight does not exist between car and pit antennas, received signals propagate as reflections. Reflected signal paths can destructively interfere with each other. This effect is called Multi-Path Fading. An Anti-Node is a point in space where Multi-Path Fading diminishes Signal Strength Received signal - db Quality is checked every 1 or 12 bytes signal threshold level Two fades are unlikely to occur at the same time Time Representation of multi-path fading The Diversity Receiving Function of the of the P192-S means that when receiving, the P192-S actively monitors the strongest signal from it s two receiving antennas. It is unlikely that an Anti-Node will occur simultaneously at both antennas, hence superior coverage can be achieved when compared to a non-diversity Receiving radio. 12 Pi P192-S Telemetry Radio Application Note

13 Pit receiver antenna To ensure that the two pit antennas are not affected simultaneously by the same Antinode, their closest points must not be closer than 0.75 metres (3/4 wavelength). For the best circuit coverage, the pit antennas need to be as high as possible. The pit antennas should be mounted at least 2 metres away from any other transmitting antenna. The antennas should be connected to the P192-S pit unit by low loss coaxial cables, Pi Research Part Number 03I-0566-variant (variant refers to the loom length, which can be specified at the time of order). If you mount two antennas on a single mast, you should mount them as far away from each other as is possible. Antenna feed looms If you are going to use your own antenna feed loom, it should be of high quality coaxial cable, with a stranded inner core. The type of cable is determined by the proposed length of the feed loom. For antenna feed looms of less than 10 metres (33 feet) in length use URM43 coaxial cable. For antenna feed looms greater than 10 metres (33 feet) in length use URM67 coaxial cable. For best results, use crimp TNC connectors for the radio and solder N type for the antenna end of the feed cable. The connectors must be kept watertight, and we recommend that you wrap them with self-amalgamating tape. 13

14 Connecting antennas CAUTION: A P192-S should only be used as a transmitter when a length of coaxial cable has been attached to the TNC connector NEAREST the AutoSport connector. If this is not done, the P192-S may damage itself, and its warranty will be void. A P192-S only transmits a radio signal from the TNC connector that is NEAREST the AutoSport connector. Both TNC connectors of a P192-S will receive radio signals. P192-S as a transmitter When a P192-S is used for transmission only, an antenna must be connected to the TNC connector NEAREST the Autosport connector. See the figure Connecting antennas below. P192-S as a receiver If a P192-S is to be used for receiving, antennas should be connected to both TNC connectors to take advantage of the P192-S diversity receiving capability. See the figure below. connect antennas to both connectors when radio is installed in the pit AutoSport connector do not connect anything here when the radio is installed in a car connect antenna here when radio is installed in a car Connecting antennas 14 Pi P192-S Telemetry Radio Application Note

15 Configuring the P192-S Radio configuration utility To enable the P192-S to be configured, a software utility application for the PC and a programming loom are supplied. The configuration utility application is supplied on a CD-ROM. To install the configuration utility application: 1 Insert the CDROM into the CD drive of the PC. The installation programme should start automatically. 2 Follow the on-screen instructions. To configure the PI92-S: 1 Connect the programming loom as shown in the next figure. telemetry connector on loom programming loom P192-S radio to serial port on PC Connecting the programming loom 2 Click Start Programs Pi Research P192-S-Config. The P192-S configuration start-up screen appears. 15

16 P192-S configuration start-up screen After a short delay the Pi Research P192-S Telemetry Radio Configuration dialog replaces the P192-S configuration start-up screen. Pi Research P192-S Telemetry Radio Configuration dialog You can change the COMM port which the configuration utility connects to. 3 Click Comms Port Setting and choose from the list. 16 Pi P192-S Telemetry Radio Application Note

17 4 Power-up the radio and click Connect. The red bar on the Connect button changes to green. The dialog also displays the message Reading Radio settings. Reading radio settings message The current Radio Frequency and Transmission Power settings are then displayed in the text boxes on the dialog. Radio Frequency Setting Note: Licensing of the P192-S is the responsibility of the radio s operator. Both the car and pit radios must be configured to communicate on the same frequency. 5 Enter the required frequency into the Radio Frequency text box. The radio can be programmed within the range 458 > 460 MHz and the frequency must be divisible by 25kHz (the radio s channel spacing). Radio power setting Radio Power should be chosen according to longest straight-line distance that the car travels from the Receive antennas. High power can overcome signal strength fading due to distance, but not major obstacles, so there is limited coverage to be gained by increasing power in situations where the transmission distance is comparatively short. Typical power settings are 1 Watt for ovals and 2 Watts for conventional road courses and street circuits. 6 Choose the required power setting from the list in the Transmission Power text box. 7 Click Set Radio Power and Frequency. The new settings are sent to the radio. The Setting up Radio message appears on the dialog. Setting up Radio message 17

18 This followed by the Saving settings for Radio message being displayed on the dialog box. Saving settings for Radio message After the settings have been saved in the radio, the following message appears. Run mode Warning message This message tells you that the radio is now in Run mode. You will have to power cycle the radio if you want to perform further configuration on that radio. If you have set a frequency outside of the valid range, the following error message appears. Error message: Set valid frequency If you have set a frequency that is not divisible by 25kHz an error message appears. 25kHz boundary error message 18 Pi P192-S Telemetry Radio Application Note

19 Read Existing Radio Settings Click Read Existing Radio Settings any time after connecting to the radio, to read the existing settings. Set Pi Defaults button It is not recommended to use the Set Pi Defaults button, unless instructed to do so by Pi Research Support. Use of this feature will disable any custom configuration that may have been performed by Pi Research. Cannot connect to radio error message If you click Connect after setting Radio Power and Frequency, and you have NOT power cycled the radio, you will get the following error message. Cannot connect to radio error message To allow you to Connect to the radio again, you must power cycle the radio. Radio not detected error message If you click Read Existing Radio Settings before you have connected to the radio you will get the following error message. Radio not detected error message 19

20 P192-S status LED s The P192-S has a number of LEDs which indicate the status of the unit. The table below lists the LEDs and their meaning when the LEDs are on. LED Colour Meaning CD Red Transmitting radio signal Orange Noise on frequency Green Receiving radio signal RD Red P192-S sending data via serial port TD Red P192-S receiving data via serial port CTS Not used (hardware handshaking). See note below RTS Not used (hardware handshaking) Note: The P192-S default settings do not have the full CTS line functionality enabled. This functionality can be enabled upon request by Pi Research. The figure below shows the location of the LEDs on the P192-S. Location of P192-S LEDs 20 Pi P192-S Telemetry Radio Application Note

21 Serial Interface The P192-S supports bi-directional RS232. Baud rate setting P192-S is supplied with a serial interface speed of 19,200 baud. When configuring a Pi Sigma MCU for telemetry baud rate, the rate must be set in three places before the setup is sent: Pi Workshop/Telemetry App/Where/ Pi Workshop/Sigma Configuration/Logger/Serial Setup/ Pi Server/Telemetry/Serial Port/ Refer to the Pi Workshop User Guide for information. Forward error correction (FEC) The P192-S transmitter encodes transmitted data with parity bits which enable the receiver to repair data packets that have been damaged during propagation of the radio signal. FEC can significantly improve the coverage levels. The additional parity information reduces the effective data bandwidth of the P192-S by approximately 16%. The P192-S radios are supplied by default with the FEC function enabled. Radios can have their FEC function disabled, enabling full use of the 19,200 bandwidth, upon request to Pi Research. 21

22 Pi Sigma stream optimization When configuring a continuous Pi Sigma telemetry stream, it is possible to optimise the configuration of the stream to significantly enhance coverage levels. Where maximisation of coverage is required, the following procedure is recommended. 1 Only send the minimum acceptable group of channels required. 2 Reduce each channel s send rates to the minimum acceptable. It is worth considering that the Pi Workshop Watch Cards are refreshed at 5Hz, hence any highly transient channels sent purely to be watched in Pi Workshop need not be sent at more than 5Hz. When a highly transient channel is logged via telemetry, or its value history is watched in Pi Workshop (e.g. as a time/ distance plot), it may be appropriate to send the channel via telemetry at more than 5Hz. 3 Assuming that the percentage of the stream used is now less than 84%, open the Data Engine Advanced Properties and select Manual Message Size. Reduce the manual message size incrementally until the stream usage equals 84%; this allows 16% room for the FEC parity information that is added by P192-S. It is not recommended that a message size smaller than 16 bytes be selected. If a P192-S radio is being used with its FEC function disabled, the stream usage should be made to equal 100%. 22 Pi P192-S Telemetry Radio Application Note

23 Minimisation of the Message Size Minimisation of the Message Size is recommended to maximise coverage levels when line-of-sight cannot be continuously achieved between the car and pit antennas. This is because when reception drops out during the receipt of a message, the data from the entire message is lost. By reducing the size of the messages, the amount of data lost when reception dropouts occur is reduced. The reason that the continuous stream usage should be maximised is because the transmitting P192-S will cease to remain in its transmitting mode after a certain time period has expired. If the continuous stream percentage is not maximised, pauses will exist between packets sent by a Pi Sigma Elite MCU. If these pauses are long enough, the P192-S will cease to remain in its transmitting mode between packets. Every time the P192-S shifts back from non-transmitting to transmitting mode, it sends a synchronisation packet. The time taken to transmit this packet introduces a delay in the receipt of the stream data at the receiving P192-S. 23

24 Transmit buffer Whenever a P192-S is in Data Transfer mode it monitors both the radio channel and the serial interface. When a data terminal device (a Pi Sigma MCU or a laptop) starts data transmission to its P192-S via its serial port, the P192-S switches into transmission mode. At the beginning of each transmission a synchronisation signal is transmitted and this signal is detected by a P192-S receiver, which then switches into receive mode. Transmission ends when a pause is detected in the data sent by the terminal device. When Forward Error Correction (FEC) is turned OFF, the P192-S internal transmit buffer memory cannot overflow. When FEC is turned ON the serial interface speed (19,200 baud) exceeds the speed of the radio interface (approximately 16,500bps), consequently data can fill the transmit buffer memory. The maximum size of the transmit buffer memory is 1kB. If the terminal device transmits so much data that the 1kB buffer fills completely, the buffer will be emptied before the transmission is restarted. If a P192-S is in receive mode (because it has successfully received a synchronisation signal from the other P192-S which is currently transmitting data), but its terminal device transmits data to it, the data will go into the transmit buffer memory. When the radio channel becomes available (when the other P192-S has finished its transmission) the buffered data will then be transmitted. 24 Pi P192-S Telemetry Radio Application Note

25 CTS (Clear to send) The CTS pin on the P192-S puts out a voltage to inform the data terminal device (Pi Sigma MCU or a laptop). CTS is active when P192-S is ready to accept data for transmission. CTS will shift into inactive state during data reception. CTS shifts back into active state when reception ends. CTS also shifts into an inactive state when the transmit buffer is in danger of overflowing. P192-S s default settings do not have the full CTS line functionality enabled. This functionality can be enabled upon request by Pi Research. 25

26 Specifications Description Operating voltage range Power consumption Frequency range Default RF output power Output data format Serial interface rate Max data rate Antenna impedance Operating Temperature range Weight Value 12 to 30 volts DC 25VA MHz and MHz 1 watt (nominal) RS baud approximately 16,500bps 50 ohms 25 to +55 C 659 grams 26 Pi P192-S Telemetry Radio Application Note

27 Connector information Connector details Connector Type Mating connector Antenna TNC TNC Data ASL006-05PA-HE ASL606-05SA-HE Note: Pi Research recommends using Deutsch MicroLite AutoSport connectors. If you use non MicroLite connectors to connect to the P192-S they may not mate correctly. Data connector pin details Pin Function Pin Function 1 +12V supply 4 RS232 Data out 2 RS232 Data In 5 Ground 3 Programming mode 27

28 Parts numbering The following table details the items supplied for one car. P192-S kit part number 30A comprises: Description Part number Qty Car antenna 01A P192-S telemetry unit 01A IEC mains lead-black-uk. 12A IEC mains lead-black-us. 12A P192-S Product information 29A Antenna UHF omni-directional 31A P192-S switch mode PSU 31A Transit case 35A P192-S AV mounting 13B Antenna mounting kit 30C P192-S pit data loom 60A P192-S programming loom 60A Pi P192-S Telemetry Radio Application Note

29 Dimensions (5.11 ) (4.80 ) (0.66 ) (3.41 ) Tx/Rx Rx only (1.25 ) (5.63 ) (6.60 ) Ø4.00 (Ø 0.16 ) three positions (2.30 ) (2.50 ) Dimensions shown in millimetres and (inches) 29

30 Declaration of conformity 30 Pi P192-S Telemetry Radio Application Note

31 Conditions Of Use The P192S is a vehicular Radio Modem intended for use in motorsport applications i.e. not on vehicles used on the public road network. For those vehicles that may be used on the public road network e.g. Rally cars, it is the responsibility of the user to verify that the type approval of the vehicle has not been compromised. FCC Authorisation This equipment has been granted FCC Equipment Authorisation as listed below. Equipment Notes: class: FCC Rule Parts Licensed Non-broadcast Station Transmitter P192-S Frequncy range (MHz) Output Watts Frequency Tolerance Emission Designator Hz 9K25F1D Hz 18K7F1D 31

32 Contact information For more information about Pi products and details of worldwide authorised agents, please contact: Pi Research Brookfield Motorsports Centre Twentypence Road Cottenham CAMBRIDGE UK Customer Support Tel +44 (0) CB4 8PS Fax +44 (0) Pi Research, Inc Haverstick Suite #275 Indianapolis IN Tel +1 (317) USA Fax +1 (317) Research Part Number: 29A E April 2004 Pi and the Pi logo are trademarks of Pi Group Limited Pi Research, Pi P192-S Telemetry Radio Application Note