Telemetry Control Box (TCB)

Contents

Description

[24-OCT-24] The Telemetry Control Box (TCB) is a telemetry receiver for devices such as our Subcutaneous Transmitters (SCT), Implantable Inertial Sensors (IIS), or Implantable Stimulator-Transponders (IST). The TCB-A16 provides sixteen antenna inputs, to which we can connect up to sixteen coaxial antennas, such as the Loop Antenna (A3015C). Each antenna input is equipped with its own dedicated receiver and power meter. The telemetry messages we record with a TCB contain not only the telemetry channel number and sample value, but also the identity of the top antenna, which is the antenna at which the message presented the greatest microwave power, and the top power, which is a logarithmic measure of the microwave power at the top antenna. The top antenna is almost always the antenna closest to the animal, so the to TCB's top antenna measurement allows us to monitor the location of animals in mazes and other complex environments. The TCB-B16 provides all the functionality of the TCB-A16, but in addition allows us to use the sixteen antennas as command transmitters, and provides four programmable, high-speed, digital input-output signals. Command transmission allows us to control devices such as Implantable Stimulator-Transponders (ISTs). The digital communication lines allow the TCB-B16 to receive timing signals and transmit telemetry information to external devices.

  
Figure: Telemetry Control Box. Left: Front View, Horizontal. Right: Front View, Vertical with PoE Switch. On the back side are sixteen BNC sockets for antenna connections and a single RJ-45 socket for Power over Ethernet (PoE).

The TCB requires only one network cable for communication and power, an industry-standard Power over Ethernet (PoE) connection. We supply the TCB with an Ethernet jumper cable so we can connect it to a PoE switch, and we sell high-reliability, fanless, PoE switches of various sizes for use with the TCB and our other PoE devices. When you order a TCB-A16, you can order up to sixteen Loop Antennas (A3015C) to go with it, depending upon how many you need to deploy in your telemetry system.

Figure: Display Panel. Activity lamps glow in proportion to sample rate. In this picture, the Detector Module Error (DMERR) light is shining, which indicates a problem with one of the internal detector modules. This light should never turn on during normal operation of the TCB. Press SHOW to turn on all the lights temporarily. Press HIDE to turn off the activity lights if they are too bright.

The TCB-A16 replaces our long-running Octal Data Receiver (A3027E, ODR) and LWDAQ Driver (A2071E) telemetry system. The TCB-A16 provides sixteen antenna inputs, the ODR provided eight. The TCB-A16 provides a top antenna measurment, the ODR does not. The TCB-A16 requires a PoE connection, the LWDAQ Driver required a 100-Base-T connection and a separate 24-V power adaptor. The TCB-B16 replaces the Command Transmitter (A3029C) and LWDAQ Driver (A2071E). The TCB-B16 provides sixteen independent, non-interfering command transmitters, the A3029C provided only one. The TCB-B16 requires no additional power supply for command transmission, the A3029C required its own 24-V power adaptor.

Versions

[01-OCT-24] The following versions of the Telemetry Control Box (A3042, TCB) are defined.

The TCB-A16 went into production in January 2023. The TCB-B16 went into production in August 2024. The TCB-B16 provides command transmission through all sixteen antennas for controlling Implantable Stimulator-Transponders (ISTs). The TCB-B16 popluates the four holes X1-X4 on the back wall with four more BNC sockets. These will provide programmable, high-speed, digital input-output for experiments in which external stimuli need to be controlled in a manner synchronous with the telemetry signals, and in which synchronizing signals need to be embedded in the telemetry recording.

Set-Up

[23-SEP-23] The TCB obtains all its power and communication through a single Power-over-Ethernet (PoE) socket. The TCB system consists of the TCB, a PoE switch, coaxial cables, feedthroughs, and Faraday enclosures. In the paragraphs below, we provide detailed instruction on setting up the TCB for communication with your computer, but ultimately refer you to the SCT setup instructions once that communication is established.

Figure: TCB Telemetry System. Four antennas are arranged in the enclosure. The TCB, an Animal Cage Camera (ACC), and the data acquisition computer are all connected to the same Power over Ethernet switch. Telemetry sensors and stimulators are implanted in animals in the Faraday enclosure.

Power Up PoE Switch: Connect power to your PoE switch. If you are not in the United States, you will need a computer power cable to connect to your local type of wall power socket, but you can be assured that the power adaptor will operate with any AC voltage 100-250 V, 50-60 Hz. Lights should illuminate on the PoE switch.

Connect TCB to PoE: Use a network cable to connect the TCB to the PoE switch. This cable can shielded or unshielded, and it can be up to ten meters long. Lights should illuminate on the TCB.

Install Software: Download and install the latest version of the LWDAQ software from here, following these installation instructions.

Connect Computer to PoE: Connect your data acquisition computer to the switch. Configure your computer to use its wired Ethernet interface with subnet 10.0.0.0 and IP address 10.0.0.20. The TCB ships with an IP address 10.0.0.x, where x is given by the last two or three digits of the serial number on the back of the TCB enclosure. The table below gives examples of serial numbers and their addresses.

You should see a link light beside the sockets you have used on the PoE switch for your computer and your TCB. Launch the LWDAQ software and try to contact the TCB using the Configurator Tool, as described here. Don't proceed until you can contact the TCB and read its EEPROM.

Figure: Telemetry Control Box Set-Up for Benchtop Enclosure with Cameras.

Continue with Telemetry Setup: Connect antennas, set up software, and test out sample transmitters with the help of our Subcutaneous Transmitter (SCT) setup instructions, which you will find here.

In the Neuroplayer, if you can use the Neurotracker to see which antenna is receiving the most power from each of your transmitters, which is the TCB's measurement of animal location.

Design

[08-FEB-24] We make the TCB-A16 by taking an Animal Location Tracker (ALT) Base Board (A3038BB-D2), putting it in a box, populating it with ALT Detector Modules (A3038DM-B2), connecting the detector modules to BNC sockets a Sixteen-Way Filtering Feedthrough (A3042FF-A) on the back wall of the box, connecting a Display Panel (A3042DP-A) to the base board, and fastening the display panel to the front of the box. We connect the ALT's RJ-45 socket to an RJ-45 feedthrough on the back wall of the box.

Figure: TCB-A16 Opened. Showing the main board and part of the straight-feedthrough board at the back.

The TCB-B16 is identical to the TCB-A16 except its antenna connections pass through a Sixteen-Way Transmitting Feedthrough (A3042TF) equipped with sixteen Transmitter Modules (A3042TM). These additional circuits provide command transmission for Implantable Stimulator-Transponders (ISTs) as well as programmable, high-speed, digital input-output on the X1-X4 BNC sockets on the back wall.

The P3042BB firmware is for the logic chip on the base board. This firmware is similar to the ALT Base Board firmware except for the addition of communication with the display board and transmitting feedthrough. We use C3038BB for the RCM6700 module, same code as for the ALT LWDAQ Relay. We use P3042DM on the detector modules. The detector modules themselves are the same A3038DM modules we use on the ALT, but they are re-configured for top antenna detection. We use P3042DP on the display panel, and P3042TF on the transmitting feedthrough.

For details of the operation of telemetry reception by the A3042BB base board and A3042DM detector module, see the Animal Location Tracker (A3038) manual. The TCB uses the same base board and detector modules as the ALT, the only differences being in firmware and the fact that the TCB antennas are not loaded onto the base board. For a description of how we communicate with the TCB ove TCPIP, see the Operation section of this manual.

Operation

[10-JUL-24] If you want to control an A3042 with your own data acquisition software, consult the LWDAQ Spectification for details of the TCPIP messages we use to communicate with the A3042. The A3042 acts like a LWDAQ System of Form C for the purpose of data acquisition. Its controller address space is defined in VHDL as follows.

constant cont_id_addr : integer := 0; -- Hardware Identifier (Read)
constant cont_sr_addr : integer := 1; -- Status Register (Read)
constant cont_djr_addr : integer := 3; -- Device Job Register (Read/Write)
constant cont_hv_addr : integer := 18; -- Hardware Version (Read)
constant cont_fv_addr : integer := 19; -- Firmware Version (Read)
constant cont_crhi_addr : integer := 32; -- Command Register HI (Write)
constant cont_crlo_addr : integer := 33; -- Command Register LO (Write)
constant cont_cfsw_addr : integer := 40; -- Configuration Switch (Read)
constant cont_srst_addr : integer := 41; -- Software Reset (Write)
constant cont_fifo_av_addr : integer := 61; -- Fifo Blocks Available (Read)
constant cont_fifo_rd_addr : integer := 63; -- Fifo Read Portal (Read)

We memory portal address is 63 (0x3F), as in all LWDAQ controllers. But the A3042's memory portal is read-only. The A3042 does not support the stream_write instruction. It does, however, provide a stream_read, and it is the stream read that we use to download telemetry data from the A3042's controller memory. The telemetry data is stored in a first-in, first-out (FIFO) buffer in the controller. To operate an TCB, the data acquisition software begins by writing any value to the Software Reset location (41), which resets the message clock, clears the message buffer, flashes the white lights, and configures the detector modules. After that, keep reading the Blocks Available location (61). Multiply the blocks available by 512 to get the number of bytes available. The maximum value of this counter is 255, so if there are more than 130 kBytes of data available, you will not know it. The TCB data is divided into six-byte message. Each message begins with a four-byte telemetry message record, which we describe in the Telemetry User Manual. After that comes the top power and the top antenna, each one byte. When we download from the TCB, we download a whole number of messages, so the number of bytes should be divisible by twenty. We now execute a stream_read and download the number of bytes we expect.

If you want to configure the TCB to record only from certain SCT channel numbers, you can do this by writing commmands into the controller using the Command Register (two bytes) and the Device Job Register. You will find Tcl code for configuring ALTs and TCBs in Receiver.tcl.

[12-FEB-24] The transmitting feedthrough A3042TF-A functions as follows. Each antenna has its own transmitter module, A3042TM-A. The transmitter module takes 3.7-V power as input and an ON signal. When ON is asserted, the module consumes 300 mA from 3.6 V and produces 23 dBm of 915 MHz. Each antenna has an RF switch requiring only one logic level for control, such as PE4259DS. When ON1 is asserted, the switch connects Antenna One to Transmitter Module One. Otherwise, the switch connects Antenna One to Detector Module One on the base board. Each transmitter module mounts on a 5 × 2 socket header at one end and is held at the other end by a standoff and screw. The power and control enter through the header. The 915MHz exits through a UMCC jack, which we connect with a 50-mm cable to another UMCC jack next to the antenna switch.

The TF is controlled by an LCMXO2-4000ZE logic chip. Connection to the base board is via four flying wires terminated in a MOLEX-4 socket. We have +5V, 0V, TX, and RX. The logic chip receives instructions from the base board via TX and sends notifications back to the base board via RX. Instructions will enable antennas, transmit telemetry command bytes, and configure the four digital input-outputs. The logic chip runs off 1.2 V and 3.0 V regulated down from +5V.

The digital IO are X1-X4 BNC sockets on the back wall of the TCB-B. Each of these has three connections to the TF logic: XEN, XD, and XC. When XEN1 is asserted, an SN74LVC1G126 drives X1 with XD1 through 50 Ω. We power the 1G126 with 5 V so that it can provide 2.5-V down a 50-Ω coaxial cable. By enabling the 1G126 and setting XD low, we provide 50-Ω termination for the X1 input. The value XC1 is a clamped version of X1 for input. On the TF, the logic chip is far from the X1-X4 sockets. We connect each of X1-X4 to the TF board with a 150-mm BNC to UMCC cable, but we still have 400 mm from the end of the coaxial cable to the logic chip. We run the logic signal down a 50-Ω microstrip transmission line to the terminating 50-Ω resistor next to the logic chip.

Power for the TMs is provided by a 380 mAhr high-current, lithium-polymer battery. Rated for 25C discharge, the battery can deliver 9.5 A for short periods of time. The battery includes its own overvoltage, undervoltage, overcurrent, and short circuit protection. It mounts on the TF circuit board and connects with a two-way socket. The battery charger is a 70-mA current source with voltage limit 4.2 V. Because the TMs are active for less than 1% of the time, the 70-mA charger is sufficient to restore the battery after bursts of 16 × 0.3 = 4.8 A. When on the shelf without power, the battery is disconnected from the circuit by a mosfet switch. Lithium-polymer batteries discharge at approximately 5% per month. The battery could drain to 15% capacity in three years without power. After that, the 70-mA current source will restore the battery to 25% capacity in half an hour.

On the Transmitter Module, we have a TLV61048 boost regulator producing +5.0 V from VBAT = 3.7 V with 90% effiency. These run all the time, consuming roughly 100 μA with no load. We have a mosfet switch to connect power to our RF oscillator and amplifier. There are two stages of RF amplification, both use SOT-89 packages. The oscillator can use the GALI-3+. With feedback through a 50-mm delay line and a 915-MHz SAW filter, we get our oscillation with +10 dBm output after stabilizing attenuator. The next stage can be GVA-92+ providing 25 dBm when saturated. The GVA-92+ requires no output matching network at 900 MHz. The recommended input matching network of 18 nH parallel followed by 5.6 pF series is designed to match a 50-Ω source to a load of 40 + 10j Ω. We can omit this network with no more than 2 dB loss of power. We add a 2-dB attenuator and a 1-GHz low-pass filter to produce roughly 23 dBm sine wave. We launch this power off the board with a UMCC jack. Total current consumption from +5V is 200 mA, or 300 mA from VBAT.

[20-MAY-24] The TCB-B16 implements a sixteen-channel command transmitter for radio-controlled implants by taking over the TCB's sixteen telemetry reception antennas for command transmission. We present the command transmission protocol in detail in the Implantable Stimulator-Transponder (A3041) manual. We reproduce below the timing diagram from the protocol.

Figure: Command Transmission Protocol.

A typical command transmission lasts ten to forty milliseconds. During this time, all sixteen TCB-B16 antennas are connected to their own dedicated 915-MHz power sources whenever the command transmission protocol requires that a HI level be transmitted. The power sources turn on and off so quickly that we can disconnect them and turn them off during each LO level, and during these LO periods, the TCB can receive telemetry signals. Reception will drop to around 50% during command transmission, and recover immediately afterwards.

Figure: Command Transmission and Reception. We have three probes on an A3041 IST circuit. Blue: Crystal radio output, VR, showing on-off 915-MHz power from Transmitting Feedthrough, 50 mV/div. Yellow: Logic level RP from crystal radio comparator, 1 V/div. Green: OND generated by logic chip, 1 V/div.

The traces above show an IST responding to a command transmitted by a single TCB-B16 antenna. Command reception is >90% for ranges ≤30 cm.

[10-JUL-24] The TCB is a LWDAQ system of Form C. It consists of a relay, a controller, and a device with two elements. Element one is the receiver on the base board with its sixteen detector modules. Element two is the array of sixteen transmitter modules on the feedthrough. Element three is the set of four digital transceivers on the back wall. The TCB-A16 provides only element one. The TCB-B16 provides elements one, two, and three. The LWDAQ protocol specifies a dozen controller jobs, but the TCB implements only the command job. A command job transmits a sixteen-bit word to a device. Because the TCB does not implement driver sockets or multiplexer sockets, we do not need to write to the controller's device address register. But we must write to the device element register to tell the controller if the command is destined for the receiver (1), transmitter (2), or digital transceivers (3). We use these sixteen-bit words to configure the receiver for channel selection and to reset the receiver. We use them to transmit commands to implantable stimulators, and we use them to configure the digital transceivers.

Power Consumption

[30-MAY-24] The TCB-A16 consumes a maximum of 8 W. The TCB-B16 peak power consumption during command transmission is 22 W. The extra 14 W is consumed by its sixteen quarter-watt radio-frequency power sources. This additional 14 W is drawn from the TCB-B16's on-board LiPo battery, which supplies 4.0 A during power transmission. This 14 W remains internal to the TCB-B16 because it must be drawn from the battery. The only power the battery draws from the TCB main power supplies is its re-charge current, which is at most 100 mA from 5 V, or 0.5 W. The logic and lamps on the TCB-B16's transmitting feedthrough consume no more than 0.5 W, so the average current consumption of the TCB-B16 cannot exceed 9 W. Command transmission is rare, so the TCB-B16's battery has plenty of time to recharge between transmissions.

Modifications

[24-DEC-22] The A304201A PCB for the display panel needs the following. Test points must be marked on back side of board. Need test points for detector control bus signals, marked on both sides. Two more mounting holes to stop the board from flexing.

[24-APR-24] In order to build the A3042TF-A1 using the A304202C printed circuit board, we perform the following modifications.

1. Solder 100 pF between Q1 and 0V. Do the same for Q2-Q4. These capacitors are C49-C52.
2. Solder two P2010, 47 Ω resistors in paralell using the R4 footprint. These are R4 and R18.

[14-AUG-24] Up until 24-APR-24 we apply the Detector Module Clock Modification, see A3038 Modifications, to the A3038BB-D2. We add C48 = 100 pF to the base of DMCK to reduce reflections off the end of the daisy chain. This modification is later superceded by the DMCK Termination Modification. In the DMCK Termination modification, we replace R41 with 47 Ω in series with 1.0 μF.

Development

[15-NOV-24] For details of the development and production of the A3042 series circuits, see their Developement page.