AstroDev Helium Radios

Transcription

1 AstroDev Helium Radios PRODUCT OVERVIEW Overview The Helium radio product line provides a CubeSat Kitcompatible communication system for extreme environment applications. Helium radios feature variable frequency selection and variable output power. They are compatible with standard amateur radio ground stations capable of communication at 1200 bps, 9600 bps, or higher bit rates using GMSK modulation. The Helium 100 series radios (He-100) are mode B transceivers; they transmit on the 440 MHz amateur radio band and receive on the 140 MHz amateur radio band. Custom frequencies are available per customer requirements. The Helium 100 series radios are available as a PC104- size board, compatible with the Cubesat Kit Bus standard developed by Pumpkin, Inc. A digital command and data interface is provided to the radios. Through this interface the radio is configured, data is received, and data is sent for transmission. A packet protocol with checksums is implemented between the host and radio for robust access. The radios communicate using a subset of the AX.25 packet protocol or a user specified binary protocol. In AX.25, only unnumbered information (UI) frames are supported. The packet source and destination call signs are configurable. In the binary mode, the radios pass through the binary data without any processing, allowing users to define custom protocols and forward error correction. Applications: Cubesat Kit systems High altitude balloon missions Rovers or other remotely operated vehicles Remote embedded systems Features: FSK/GMSK transceiver Frequencies: o TX: MHz or MHz o RX: MHz or MHz Receive sensitivity: BER 10-3 Output transmit power: 100 mw 3 W Input voltages: o Logic: 3.3V o Transmitter 5-16V Power usage: o Receive: < 200 mw 1 o Transmit: < 6 W 1 Maximum data rate: 38.4 kbps (higher speeds under test) Full duplex Protocol support: o Subset of AX.25 o User defined through a transparent byte-level interface. Serial interface: 3.3V UART Form factor (CubeSat Kit compatible): o Stand alone board Operating Temperature: -30 to +70 C Options: AES 128 or 256 Encryption He-100 emits RF radiation that may interfere with the use of other devices. Users must maintain proper licenses during operation. He-100 is static sensitive, take the necessary precautions Figure 1-- He-100 radio He-100 requires proper termination of transmitter in 50 Ohm load during operation. 1 Full ready state for transmission and reception. Lower power receive and transmit modes are user configurable. Astronautical Development, LLC Revision 0.9 7/26/2009

2 Table of Contents Absolute Minimum and Maximum Ratings...3 Physical Characteristics...3 Typical Performance Characteristics...4 Radio Connection Information...7 System Block Diagram...7 CSK Interface Header Description...7 Concept of Operations...8 Command and Data Interface...8 Radio Configuration...8 Data Protocol Description...8 Transmit Overview...9 Receive Overview...9 Broadcast TNC Mode...9 Switching Radio Modes...9 Safe Operations...10 Example communications session, sending a No-Op command:...10 Transceiver Serial Communications Interface Description I Messages...11 No-Op Message...12 Reset Message...12 Transmit Message...12 Get Transceiver Configuration Message...12 Set Transceiver Configuration Message...12 Buffer Query Message...14 Telemetry Point Query Message...14 Transceiver Serial Communications Interface Description O Messages...15 No-Op Message Response...15 Reset Message Response...15 Transmit Message Response...15 Get Transceiver Configuration Message Response...15 Set Transceiver Configuration Message Response...16 Buffer Query Message Response...16 Telemetry Point Query Message Response...16 Helium Configuration Program...17 Dimensions and Form Factor...20 Protecting Against Electrostatic Discharge...20 Trademarks...21 Disclaimer...21 Notes...21 Astronautical Development, LLC Revision April 2009 Page 2 of 21

3 Absolute Minimum and Maximum Ratings Parameter Symbol Min. Nom. Max. Units Operating temperature T OP to C Interface Voltages and Currents: Voltage on Battery Pin (CSK Bus) V batt V Current on Battery Pin I bat A Voltage on System Pin (CSK Bus) V sys V Current on System Pin I sys 0.10 A Voltage on UART Pins (CSK Bus) V uart V Voltage on Reset Pin (CSK Bus) V reset V Physical Characteristics Parameter Notes Symbol Min. Typ. Max. Units Mass 78 g Maximum Height above PCB mm Maximum Height below PCB mm PCB Width mm PCB Length mm PCB Thickness mm 1 CSK Standard Board Astronautical Development, LLC Revision April 2009 Page 3 of 21

4 Typical Performance Characteristics 6 Transmit Output Power Versus Power Command Transmit Output Power (W) V VBatt 7.5V Vbatt 5V VBatt Command Power Setting Figure 2 -- Output Power vs. Power Setting. Total Power Consumption Versus Power Command V VBatt 7.5V Vbatt 5V VBatt Total Power (W) Command Power Setting Figure 3 -- Power Consumption vs. Power Setting. Astronautical Development, LLC Revision April 2009 Page 4 of 21

5 Ref 27 dbm Samp Log 10 db/ Atten 40 db VAvg 10 W1 S2 S3 FC AA Center 138 MHz Res BW 300 Hz Span 50 khz VBW 300 Hz Sweep s (600 pts) Figure 4 He-100 GFSK 9600 Baud Output Spectrum. Figure 5 Receive mode BER vs. Input Power Astronautical Development, LLC Revision April 2009 Page 5 of 21

6 RSSI Linearity 0-20 RSSI Level (dbm) RF Input Level (dbm) RSSI Telemetry Level Actual RF Input Level Figure 6 -- RSSI Linearity Astronautical Development, LLC Revision April 2009 Page 6 of 21

7 Radio Connection Information System Block Diagram Ant Power Amplifier Transmitter Module MSP430 Processor Ant Receiver Module Reset Supervisor VBattX 3.3V GND P3.1 P3.3 CubeSat Kit Header P3.6 P3.7 Reset Figure 7--System block diagram of the Helium Radios. CSK Interface Header Description CSK Header 1 (H1) CSK Header 2 (H2) Figure 8 -- Cubesat Kit Radio Interface Pins Table 1 -- Radio/CSK Pinout. Radio Pin CSK Pin # CSK Pin Name Typical Current Draw Summary RADIO_UART_RX 18 P3.6x <2 ma Radio UART interface Rx. RADIO_UART_TX 17 P3.7x <2 ma Radio UART interface Tx. RADIO_3.3VSYS 27 & 28 VCC_SYS <75 ma Radio 3.3V Voltage RADIO_GND 29 & 30 & 32 GND N/A Radio Ground RADIO_VBATT 45 &46 VBATTx <1 Amp Radio Voltage for Power Amplifier Astronautical Development, LLC Revision April 2009 Page 7 of 21

8 Concept of Operations Command and Data Interface Header (8 Bytes) Payload (0 to 255 Bytes) Payload Check Sum A (1 Byte) Payload Check Sum B (1 Byte) Figure 9--Packet structure for the Command and Data Interface (CDI). Sync Characters (2 Bytes) Command Type (2 Byte) Payload Size (2 Bytes) Header Check Sum A (1 Byte) Figure 10--Description of the packet header used in the CDI. Header Check Sum B (1 Byte) Users interface to the Helium radios through the Command and Data Interface (CDI). Through the CDI, users configure the radio, query radio-specific telemetry points, send data to be transmitted, and request data that was received. Users access the CDI through the UART port at 0-3.3V levels The packet format for the digital interfaces is pictured above in Figure 9. It consists of an 8 byte, fixed length header, a variable payload segment from 0 to 255 bytes, and 2 check sum bytes. The header is described in Figure 10. The sync characters of the header are a two byte sequence 2 : Sync Character 0: 0x48 or H Sync Character 1: 0x65 or e The next two bytes in a message header are the command type. Commands can be divided into two types representing the direction of the communications. Data entering the radio is noted as I-messages. I-messages are command types that begin with 0x10. Data leaving the radio is noted as O-messages. O-messages are messages that begin with 0x20. The full command list is given later in this documentation in section Transceiver serial communications interface description. The Payload Size field of the header is a two byte, unsigned short integer containing the total number of bytes in the packet payload. The most significant byte (MSB) is given first. The maximum payload size is 255. Two checksum bytes are appended to the header for error detection. The 8-bit Fletcher algorithm (see RFC 1145 which describes TCP) is used to calculate the checksums. The algorithm works as follows: A buffer, Buffer[N], contains data over which the checksum is to be calculated. The two checksum 2 Bit stuffing is not needed because checksums and packet lengths are used. values (CK_A and CK_B) are 8-bit unsigned integers only. Note, if you implement it with larger sized integers, be sure to mask both CK_A and CK_B with 0xFF after the calculations complete to ensure they are 8-bit. Psuedo-code for checksum calculation is given below. CK_A = 0, CK_B = 0 For(I=0;I<N;I++) { CK_A = CK_A + Buffer[I] CK_B = CK_B + CK_A } This loop calculates CK_A and CK_B which are then appended to the header. Following the header is the packet payload, which has a length as specified in the header. A payload checksum is then used to verify the accuracy of the payload. The checksum is calculated across all pertinent bytes of the message excluding the two sync characters of each message He. Radio Configuration The default radio configuration is set at factory load during radio acceptance testing. This default configuration is stored in flash and is applied during power up and soft reset. The user can change the radio configuration after radio processor power up by providing a valid configuration command. The configuration message can change multiple settings at once. Changes take effect immediately, however the user should allow a settling time of at least 250 ms for settings to be applied. Default settings are described in section Transceiver serial communications interface description. Data Protocol Description Helium radios support two types of packet protocol modes used over the radio: user defined and AX.25. In the user-defined mode, the radios do not process packet payloads for transmitted and received data. Data is passed transparently between the radio and the controlling device over the CDI. This enables the Astronautical Development, LLC 2008

9 user to define custom packet formats that may incorporate such capabilities as forward error correction, encryption, and whitening. In the AX.25 mode, the radios implement a subset of the AX.25 packet radio protocol as defined by Only the handling of UI frames is implemented, not full connected mode. Users are able to configure the source and destination call signs, the packet length, and the TX tail and head parameters (see the command list in Table 2). The radio performs all packetization functions such as bit stuffing and check sum calculations. Transmit Overview Radio transmissions are performed based on the radio mode setting. All data received from the hardware interface is immediately transmitted unless the radio is busy with a current transmission. Data to be transmitted will be temporarily retained in the transmission buffer based upon the RF baud rate and the buffer length. During transmission, the radio operates the as described previously in the Command and Data Interface section of this document. The transmission of data in binary mode requires that the following settings be defined. - Encoding method 3 - Scrambling function 3 - Flag or synchronization bytes 3 - Checksum method 3 These parameters default to standard AX.25 settings and are defined later in section Transceiver serial communications interface description. Receive Overview Radio receive operations are performed based on the radio mode setting and hardware interface method. The following list describes the methods. - UART: Binary mode, non-polled only; AX.25 mode, broadcast TNC During reception, the radio maintains the interface as described previously in the Command and Data Interface section of this document. When reading data in a polled method the delivery of data consists of the He header, followed by the command type and the payload size. The raw data received is placed into the payload section of the message. The RF reception in binary mode requires the user to define several key parameters in the radio configuration command. - Encoding method 3 - Scrambling function 3 - Flag or synchronization bytes 3 - Checksum method 3 These parameters default to standard AX.25 settings and are defined later in section Transceiver serial communications interface description. Broadcast TNC Mode The TNC mode is modeled after a standard TNC interface in conversation mode. For packet reception, the radio interprets the AX.25 communication header and reduces it. Each packet is terminated with the 0x0D character, or carriage return. The header of the message is formed into source and destination with delimiters of > and :. An example reception is provided below, where (0x0D) is the last character and PAYLOAD is the entire packet payload in raw form. KA4YZR> KA4KKF:PAYLOAD(0x0D) To transmit in TNC mode the user simply transmits the payload followed by the terminating 0x0D to the radio. This termination tells the radio to send the previously submitted bytes. If the payload exceeds 256 bytes the radio will automatically transmit and continue to buffer characters until either the 0x0D command is provided or the next 256 byte maximum is reached. (USERS: Please note this is under review. It has been requested that the terminating character 0x0D NOT be used when sending a received packet out of the radio. This is because some users have raw data in the payload of the message that may contain the 0x0D character. It is proposed that a character combination be used ~ followed by 0x0D) Switching Radio Modes The radio mode may be switched between TNC and binary mode. To switch from TNC to binary mode the user should send the ~ character followed by the 0x0D character. To switch from the binary mode to TNC mode, a valid configuration message should be sent. 4 Not available in v0.6 Page 9 of 21

10 Safe Operations Helium radios are sensitive electronic device. Exposure to electrostatic discharge (ESD) can destroy electronic components. Proper ESD protection and handling is required. Proper antenna loading is required for the Helium radios. A dummy load compatible with the frequency range and output power level or a frequency matched antenna is needed to ensure proper transmissions. Improper loading on the output of the radio can permanently damage the transmitter. Example communications session, sending a No-Op command: First, the user implements a No-Op request. This is performed by loading an array with the proper values and sending them to the radio over a serial connection, below in pseudo code. buffer[0] = SYNC_1; //This is a #define value of H buffer[1] = SYNC_2; //This is a #define value of e buffer[2] = I_MESSAGE_TYPE; //This is a #define value of 0x10 buffer[3] = NO_OP_COMMAND; //This is a #define value of 0x01 buffer[4] = 0x00; //There is no payload size information in a No-Op request buffer[5] = 0x00; calculate_header_checksum(&buffer[2]); //The first two synch bytes are not included in the checksum serial.write( &buffer[0], 8 ); //send the information out your serial port The radio then responds to the request with either an acknowledge or not-acknowledge. An acknowledge is a response with the value 0x0A0A in the payload bytes. For example: Byte[0] = 'H'; Byte [1] = 'e'; Byte [2] = 0x20; Byte [3] = NO_OP_COMMAND; Byte [4] = 0x0A; Byte [5] = 0x0A; Byte [6] = Checksum A; Byte [7] = Checksum B; A not-acknowledge is a response with 0xFFFF in the payload bytes. For example: Byte[0] = 'H'; Byte [1] = 'e'; Byte [2] = 0x20; Byte [3] = NO_OP_COMMAND; Byte [4] = 0xFF; Byte [5] = 0xFF; Byte [6] = Checksum A; Byte [7] = Checksum B; This is how most communications are performed with the radio. When messages include a payload, the response or command must contain a payload length value and the payload with the message. Page 10 of 21

11 Transceiver Serial Communications Interface Description I Messages This section provides an overview of I-Messages, commands sent from the host to the radio over the CDI. Table 2 -- Summary of I Commands. Op Code Command Name Arguments Total Bytes Summary 0x1001 No-Op - 0 No-op command. Increments command processing counter. 0x1002 Reset - 0 Reset radio processors and systems. 0x1003 Transmit Bytes n Send n number of bytes to radio board. 0x1004 Get Transceiver - 0 Read radio configuration. Configuration 0x1005 Set Transceiver Configuration 42 Set radio configuration. Configuration Structure 4 0x1006 Buffer Query - 0 Request return of number of buffers used in transmission queue 0x100A Telemetry - 0 Query a telemetry frame. 5 4 Refer to transceiver configuration message description. 5 Telemetry points and their code are described in Table 17. Page 11 of 21

12 No-Op Message Table 3 -- No-Op Message, Op Code 0x1001. Op Code 0x1001 Byte Offset Value Name Description No Arguments Reset Message Table 4 -- Reset Message, Op Code 0x1002. Op Code 0x1002 Byte Offset Value Name Description No Arguments Transmit Message Table 5 -- Transmit, Op Code 0x1003. Op Code 0x1003 Byte Offest Value Name Description Bytes 0 Raw Bytes n 255 Raw bytes to transmit Get Transceiver Configuration Message Table 6 -- Get Transceiver Configuration, Op Code 0x1004. Op Code 0x1004 Byte Offset Value Name Description No Arguments Set Transceiver Configuration Message Table 7 -- Set Transceiver Configuration, Op Code 0x1005. Op Code 0x1005 Byte Offest Value Name Description Radio Mode 0 0x01 Mode Binary Mode 0x02 AX.25 Mode 6 Radio Time 1 0 to 2 32 Time Time of powered operation LSB is 2500 millisecond Interface Baud Rate 5 Interface Baud Rate 0x x x x x x Tx RF baud rate 6 0x01 Tx RF Baud Rate Rx RF baud rate 7 0x01 Rx RF Baud Rate The baud rate used to communicate with the radio Transmitter 11 0x00 to 0x0A Power Level default 0x0A, Refer to Figure 2 -- Output Power Level Power vs. Power Setting. Reserved 12 Reserved 6 Default Setting Page 12 of 21

13 Channel Rx Frequency Helium Radio Product Line 13 Chan Rx Frequency Reserved 17 Reserved Channel Tx Frequency AX25 Mode source AX25 Mode destination AX25 Mode Tx delay AX25 Mode Tx delay end 18 Chan Tx Frequency 22 char *7 Source Call Sign 29 char *7 Destination Call Sign Frequency of channel operation. Given in KHz, 6 digits. Example Frequency of channel operation. Given in KHz, 6 digits. Example AX.25 Source Call Sign, 7 characters, default NOCALL, not a null terminated string AX.25 Destination Call Sign, 7 characters, default NOCALL, not a null terminated string to 255 Tx Delay AX.25 Tx Delay in hundredths of seconds, default 0.01 s to 255 Tx Delay AX.25 Ending Tx Delay, default 100ms End AX25 Mode PID 38 PID AX.25 PID, default 0x60 = UI Packet 39 Encoding Reserved 40 Scrambling Reserved 41 Synchroniza Reserved tion 42 Checksum Reserved Example Configuration Structure: typedef struct { uint_1 radio_interface_mode;//radio Interface mode (default binary = 0x00) uint_1 RF_mode;//Radio RF Mode (default AX25=0x01) uint_4 radio_time;//radio Time (default 0x0000) uint_1 interface_baud_rate;//radio Interface Baud Rate (default 9600=0x03) uint_1 tx_rf_baud_rate; //Radio TX RF Baud Rate (default 9600=0x02) uint_1 rx_rf_baud_rate; //Radio RX RF Baud Rate (default 9600=0x02) uint_1 rx_buff_size; //Rx Buffer Size (default 0x06) uint_1 tx_buff_size; //Tx Buffer Size (default 0x04) uint_1 tx_power_amp_level; //Tx Power Amp level (default max = 0x0A) uint_1 rx_mode; //Channel Rx Mode (do not implement) uint_1 tx_mode; //Channel Tx Mode (do not implement) uint_4 rx_freq; //Channel Rx Frequency (default radio specific) uint_4 tx_freq; //Channel Tx Frequency (default radio specific) unsigned char source[6]; //AX25 Mode Source Call Sign (default NOCALL) unsigned char destination[6]; //AX25 Mode Destination Call Sign (default NOCALL) uint_1 tx_delay; //AX25 Mode Tx Delay (default 10ms) uint_1 tx_delay_end; //AX25 Mode Tx Delay End (default 100ms) uint_1 pid; //AX25 Mode PID (default 0x60) uint_1 binary_encode_method; //Binary Mode Encoding Method uint_1 binary_scrambling_method; //Binary Mode Scrambling Function uint_1 binary_flag_sync_byte; //Binary Mode Flag or Synch Bytes uint_1 binary_checksum_method; //Binary Mode Checksum method uint_1 spare; } RADIO_CONFIGURATION_TYPE; 7 Default frequency depends on product range selection Page 13 of 21

14 Buffer Query Message Table 8 -- Buffer Query, Op Code 0x1006. Op Code 0x1006 Byte Offset Value Name Description No Arguments Telemetry Point Query Message Table 9 -- Telemetry Point Query Message, Op Code 0x1008. Op Code 0x100A Byte Offset Value Name Description No Arguments Page 14 of 21

15 Transceiver Serial Communications Interface Description O Messages This section provides an overview of O-Messages, messages the sent to the host from the radio over the CDI. Note: All messages are replied to by the receiver telling the user whether a message was accepted or rejected. Please refer to example communications of No-Op command in previous section. Table Summary of O Responses. Op Code Response to Arguments Total Bytes Description Command Name 0x2001 No-Op - 0 Acknowledge response to No-op command. 0x2002 Reset - 0 Acknowledge response to valid reset command. 0x2003 Transmit - 0 Acknowledge response to a valid transmit command 0x2004 0x2005 Get Transceiver Configuration Set Transceiver Configuration Configuration Structure 8 42 Response to read radio configuration, returns entire configuration structure - 0 Acknowledge response to radio configuration set. 0x2006 Buffer Query N_BUFFERS_USED 1 Response to buffer query. Returns depth used of transmission buffer. 0x200A Telemetry Telemetry Structure 9 TBD Query telemetry points No-Op Message Response Table No-Op Message Response, Op Code 0x2001. Op Code 0x2001 Byte Offset Value Name Description No Arguments, Standard Acknowledge Reset Message Response Table Reset Message Response, Op Code 0x2002. Op Code 0x2002 Byte Offset Value Name Description No Arguments, Standard Acknowledge Transmit Message Response Table 13 Transmit Response, Op Code 0x2003. Op Code 0x2003 Byte Offest Value Name Description No Arguments, Standard Acknowledge Get Transceiver Configuration Message Response Table Get Transceiver Configuration Response, Op Code 0x2004. Op Code 0x2004 Byte Offset Value Name Description 8 Refer to transceiver configuration message description 9 Telemetry points and their code are described in Table 17. Page 15 of 21

16 Returns transceiver configuration as described in the Set Transceiver Configuration, Op Code 0x1005 Set Transceiver Configuration Message Response Table Set Transceiver Configuration Response, Op Code 0x2005. Op Code 0x2005 Byte Offest Value Name Description No Arguments, Standard Acknowledge Buffer Query Message Response Table Buffer Query Response, Op Code 0x2006. Op Code 0x2006 Byte Offest Value Name Description Used Buffers 0 0 to 6 Buffers Number of transmission buffers used Telemetry Point Query Message Response Table Telemetry Point Query Message Response, Op Code 0x200A. Op Code 0x2008 Number of Commands Byte Offest Type Value Name Description 0 n NCMD Number of processed commands received by radio controller. Processor Temp. 2 C T1 Internal temperature of MSP430 processor. RF Front End Temp. 4 C T4 Temperature of the RF components in RF front end. RSSI 6 db RSSI RSSI, receive signal strength indicator. 10 PLL Lock Detect 10 n PLLLock PLL Lock Detect Boolean Bytes Received 12 n N_RX Number of bytes received. Bytes Transmitted 16 n N_TX Number of bytes transmitted. Example Telemetry Structure: typedef struct telem_type { uint_2 op_counter; sint_2 msp430_temp; sint_2 rf_front_end_temp; float rssi; uint_2 pll_lock; uint_4 bytes_received; uint_4 bytes_transmitted; } TELEMETRY_STRUCTURE_type; 10 Receive channel only Page 16 of 21

17 Helium Configuration Program AstroDev has focused on implementing products that are user friendly and supported in both the hardware and software areas. To further ease the integration of the Helium radio into CubeSat platforms AstroDev has developed a configuration program that can communicate with the He-100 over a serial interface. To use this program, the user needs a USB to serial or serial port installed in their computer. The serial port must then be converted to 3.3V UART levels as needed. The UART should then be plugged into the CubeSat UART pins on the CSK header and ground must be connected. The first tab of the Helium Configuration Program is the comm setup page, Figure 11. The communications setup page allows the user to select the interface baud rates and the Windows com port that correspondes to the serial interface. Figure Helium Configuration Program - Comm Setup Page The second tab of the Helium Configuration Program is the configuration page, Figure 12. The configuration page allows the user to setup the He-100 radio. Two buttons, read configuration and write configuration communication with the radio to either read or set the radio settings. Page 17 of 21

18 Figure Helium Configuration Program - Configuration Page The third tab of the Helium Configuration Program is the communications page, Figure 13. The communications page allows the user to transmit data to and from the radio in different modes. There is a transmit window and receive window that display ASCII information. The transmit window allows the user to enter information in TNC mode and transmit packets using the enter key. The buttons across the bottom of the page allow the user to send binary mode packets that are predefined. Page 18 of 21

19 Figure Helium Configuration Program - Communications Page Page 19 of 21

20 Dimensions and Form Factor Compatibility with the CubeSat Kit: Stand alone full board in parallel with the FM430. Figure Radio Board Layout 11 Protecting Against Electrostatic Discharge CAUTION: Disconnect the He-100 radio from power source before removing from operating environment. Electrostatic discharge (ESD) events can harm electronic components inside the He-100. Under certain conditions, ESD may build up on your body or an object, such as an antenna, and then discharge into another object, such as the He-100. To prevent ESD damage, you should discharge static electricity from your body before you interact with any electronic components. You can protect against ESD and discharge static electricity from your body by touching a metal grounded object (such as an unpainted metal surface such as your antistatic matt) before you interact with anything electronic 11 All units are in mils. Page 20 of 21

21 devices. When connecting an antenna or power plug to the He-100, you should always ground both yourself and the CubeSat structure before connecting it. You can also take the following steps to prevent damage from electrostatic discharge: When unpacking the He-100 from its shipping carton, do not remove the radio from the antistatic packing material until you are ready to install the component. Just before unwrapping the antistatic package, be sure to discharge static electricity from your body by wearing an antistatic wrist strap. When transporting the He-100, first place it in an antistatic container or packaging. Handle the He-100 in a static-safe area. If possible, use antistatic floor pads and work bench pads. Trademarks In progress. Disclaimer All information in this document is subject to change at anytime. Look for continued updates at: Helium radios are sold as test devices and require users to gain experimental license from the FCC for use in terrestrial and CSK satellite missions. Notes Page 21 of 21