XMT-G (GPS Synchronized) TRANSMITTER CONTROLLER MANUAL

XMT-G (GPS Synchronized) TRANSMITTER CONTROLLER MANUAL Zonge International, Inc. 3322 East Fort Lowell Road, Tucson, AZ 85716 USA Tel:(520) 327-5501 Fax:(520) 325-1588 Email:zonge@zonge.com

Note: This manual will cover the operation of the new XMT-G (GPS) Transmitter Controller. It is assumed the user is familiar with the XMT-32S (standard XMT) manual and usage. This manual primarily covers the differences between the XMT-G and the XMT-32S. Overview: The XMT-G is a GPS-locked controller for Zonge transmitters. In addition to location, the GPS satellites provide extremely precise timing information. This allows the XMT-G to be held in sync with a similarly equipped GDP-32(G) in a remote location without the use of a (possibly kilometers long) synchronization cable. Operation: The GPS synchronization of the XMT-G is completely autonomous and does not require tuning or setup. Information is, however, provided to the user to determine that the synchronization is operating correctly. The only setup necessary is that of any XMT, namely the desired Period & Duty settings. Controls and Front-Panel Connectors: (numbers in parentheses correspond to labels on graphic) (1) Charge connector: This will accept a connection from a Zonge UC-2 charger (lead-acid battery models), or a UC-LI charger (lithium battery models). The connector is keyed to prevent a mismatch between charger and batteries; do not force the wrong connector to mate. Lead-acid batteries may be charged while the unit is powered, to ensure a full charge with lithium batteries, please power down before charging. XMT-G Manual Zonge International Page 2

(2) Re-Sync / Tx-Off Button: The reset switch will DISABLE the transmitter output immediately by setting the Duty pin to 5 Volts. When the GPS/Manual Sync Switch (5) is in the Gps" position, it will also reboot all the Gps and synchronization circuitry into a known state, and restart the synchronization process, which may take a few minutes to complete. Do not attempt to transmit during this time (unless utilizing manual synchronization) as the transmitter and GDP will not be synchronized in time until complete. When the Gps/Manual Sync Switch (5) is in the Manual" position, pressing this switch initiates a manual synchronization between the XMT and GDP. (3) Duty Cycle Switch: Switches from 50% to 100% Duty cycle. Note that changes made from the duty cycle menu will override the setting of this switch, and, conversely, toggling this switch will override any selections made from the duty cycle menu. (4) Phase / Batt Switch: Batt setting shows the battery voltage on the meter, in Volts. Phase setting shows the relative difference between XMT Period (internal) and GDP Period (external on "I/O" connector), a meter reading of mid-scale (12) is desired when GPS's are locked and in sync. An exact reading of the phase difference is available on the LCD (see below). (5) GPS Sync / Manual Sync Switch: Must be on "Time Series" to utilize GPS synchronization. In the "Manual" position, operation is identical to the original XMT-32S, and the GPS is ignored (although GPS status such as UTC time and latitude/longitude is still available). Note that toggling this switch to the GPS position after manual synchronization will de-synchronize the XMT and GDP, and necessitate an additional manual synchronization procedure. For this reason, this is a locking switch; lift up on the actuator to toggle the switch. (6) Mode Button: Used to cycle through types of available information on the LCD (see below). (7) Up Button: Used to cycle through items on an LCD menu, or to change Period & Duty (when in Period/Duty mode, indicated by the current setting for Period on the LCD). (8) Down Button: Same as Up button, reverse order. (6+7+8) GPS Reset & ReSurvey: Moving the XMT requires a re-survey (30 minute average) of the exact location in order to produce accurate time. This should begin automatically, but can be started manually by holding the three "Mode", "Up", and "Down" buttons in simultaneously. The operator should then see "RESVY?10" on the display, and has 10 seconds to press the "Reset" button to initiate a resurvey. Note that, once again, this process will take approximately 30 minutes to complete, and is irreversible. (9) Meter: When the Phase/Batt Switch (4) is in the Battery position, this displays the battery voltage in volts. Note that lead acid batteries are considered in need of charge below 11V, whereas lithium cells retain very little capacity below 13V. When the Phase/Batt Switch (4) is in the Phase position, and the GPS/Manual Sync Switch (5) is in the Manual position, the meter indicates the relative manual synchronization state between the crystal oscillator in the XMT XMT-G Manual Zonge International Page 3

and that in the connected GDP. This is a detailed procedure; please see GDP manual for further information. (10) Power switch: Connects or disconnects the battery from the XMT electronics and crystal oscillator. When in manual sync mode, the GDP and XMT will need to be manually resynchronized with every power cycle - for this reason, the power switch contains a locking pin to prevent accidental power cycling. To operate the power switch, pull the locking pin out of the face of the switch with a thumbnail and rotate the switch. (11) Sync Out Banana Jacks: A buffered version of the transmitter control signal ( Period in Zonge nomenclature) is present on these connectors for use in the XMT <-> GDP manual synchronization procedure. (12) Internal GPS Antenna Connector [not shown]: The coaxial cable from the embedded GPS antenna on the lid of the XMT is typically connected here. Alternative antennas could also be utilized, but connecting them to the N coaxial connector at the rear of the XMT allows the lid to be closed to keep the controls clean during operation. (13) Internal wireless antenna connector [not shown]: The coaxial cable from the embedded wireless antenna on the lid of the XMT is typically connected here. If communication between the XMT control software on a laptop computer and the XMT cannot be established, check this connection to ensure it has not loosened during operation. (14) Battery compartment [not shown]: The thumbscrews to the right of the main control panel may be removed to replace the battery. (15) Transmitter control connector [not shown]: the cable that connects the transmitter to the XMT is attached here, or alternatively, the sync cable is connected between here and a GDP when performing manual synchronization; the XMT is then relocated to the transmitter s position, and the transmitter control cable is reinserted. (16) External GPS Antenna Connector [not shown]: The coaxial cable from an optional GPS antenna is typically connected here. This is useful in situations where the XMT must be located in a position where the internal antenna on the lid is prevented from seeing a clear view of the sky for acquiring satellites. XMT-G Manual Zonge International Page 4

LCD Display and Menus: The LCD display is a multi-function device intended to show status and current settings for all parameters of the XMT-G. The Mode Button switches between main modes / menus, and the Up & Down buttons switch between sub-modes / menus Main modes / menus: GPS: Period: Duty: Time & Date: Versions: Up & Down buttons cycle through all GPS information. Up & Down buttons choose the desired operating Period (Frequency). No sub-menu items, used for adjusting Period only. Up & Down buttons choose the desired operating Duty Cycle (not absolute; given as a percentage of the period). Changing this value will override the setting of the duty cycle toggle switch, and moving the switch will override any selection made via this menu. No sub-menu items, used for adjusting Duty only. Shows the current GPS time, which generally lags UTC (Universal Coordinated Time) (previously Greenwich Mean Time or GMT) by 13 or more seconds, adjusted yearly. Up/Down should cycle between time & date. No sub-menu items. Up & Down cycle through all available version information. Synchronization: Up & Down cycle through sync quality data. Configuration: GPS Menu Items: Survey Status: GPS Lock: Antenna: Allows device behavior to be modified. Any changes made via this menu should persist across power cycles (reboots). "GPS Svyd" indicates that the self-survey required for accurate timing information has been completed, otherwise percent completion is shown. "GPS Lock" indicates that the GPS is fully operational, otherwise any items preceding a successful lock are shown. Note that an almanac is not strictly necessary for accurate timing and will load in 15-30 minutes of operation. The GPS can detect a missing, cut or shorted GPS antenna cable. "Antna OK" indicates the antenna is operating nominally. Number of Satellites: It is desirable to have at least 5 satellites for a stable synchronization, although as few as 3 may be acceptable in some situations. XMT-G Manual Zonge International Page 5

DOP: Latitude: Longitude: Versions Menu Items: Serial Number: SW: FW: GPS: ( Dilution of Precision ): A GPS-centric metric for the quality of the GPS data. Current latitude is shown with "N" or "S" taking place of the decimal point (i.e. 32N2645 indicates 32.2645 or 32,2645 degrees North). Current longitude is shown with "E" or "W" taking place of the decimal point (i.e. 110W9219 indicates 110.9219 or 110,9219 degrees West). Shows device serial number. Shows software build number. Shows firmware build number. Shows GPS firmware revision. Accuracy Menu Items: X: Shows crystal accuracy over last 10 seconds vs. GPS time. Units are parts per billion. Ideal synchronization would show a value of zero. When GPS lock is lost, "NoXtalLK" is shown. Ph: Xtal D/A: Shows difference between internal Period signal, and Period connected to external "I/O" connector (usually GDP), in nanoseconds. Ideal synchronization would show a value of zero. When GPS lock is lost, or no GDP is connected to the I/O port, "PhaseErr" is shown. Shows the current value of the D/A that tunes the internal clock to match the GPS clock. Xtal Freq: Shows current frequency of the internal clock. When fully synchronized in GPS mode, this should reflect the ideal value of 4907360Hz. Configuration Menu Items: Root-2 Frequencies: Enable or disable the display/use of the Square-Root-of-2 frequencies. The period menu will cycle through all available modes sequentially; when Root-2 is disabled, this will entail the standard powers-of-2: 1, 2, 4, 8, etc. When Root-2 is enabled, those frequencies will be interleaved in the expected order: 1, 1.4, 2, 2.8, 4, 5.6, 8, etc. XMT-G Manual Zonge International Page 6

TRANSMITTER CONTROL INTERFACE (GDP-32 II Manual, Section 18.6) The GGT series transmitters use a twenty milliamp control signal with a rise and fall time of less than one microsecond. There are two control signals used; Transmitter on/off and Polarity. 1. TRANSMITTER ON / OFF. This signal is used in the time domain mode to turn off the transmitter when needed depending on the duty cycle required. 2. POLARITY. This signal controls the output polarity of the transmitter. When the signal is supplied the transmitter reverses the output polarity from the rest state. The timing diagram below shows the relationship between the two signals for a fifty percent duty cycle. Transmitter Control MS Connector: Polarity: A Ground: B, E (Need to be shorted together) Transmitter ON/OFF: C (With no connection, default is ON) Duty cycle: D XMT-G Manual Zonge International Page 7

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Manual Syncing SYNCHRONIZING TIMING CIRCUITS (GDP-32 II Manual, Section 6.2) Frequency Adjust and Synchronizing Operations The timing circuits of the XMT and the GDP-32 II are comprised of an ultra-stabilized 4.980736 MHz oscillator and a digital counter chain providing a binary sequence of frequency divisions. Frequencies on the XMT transmitter controller are selectable from a push-button panel switch. Frequencies on the GDP are selectable from a menu screen under the control of the on-board computer. To ensure that the timing edge of the transmitter controller (i.e. the transmitter output) and the receiver waveforms coincide exactly throughout the day, two adjustments must be made: First, the two 4.980736 MHz crystals must be adjusted to EXACTLY the same frequency to prevent the phase drift. Second, the counter chains in the XMT and GDP-32 II must be reset so that the switching edges of both occur simultaneously (i.e. the waveforms are synchronized.) The GDP uses the counter waveform to determine the polarity of the transmitted waveform and the on/off cycle in the case of time domain. Both of these adjustments require that the synchronization cable be connected between the XMT and GDP-32 II. The synchronization cable connects the GDP-32 II 4.980736 MHz oscillator output to the XMT phase detector. The detector displays the frequency difference between the two oscillators on the XMT meter. Each complete swing of the meter represents one cycle of 4.980736 MHz or 0.2 microseconds ( sec) of time shift. The following table shows the phase shift in milliradians (mr) per meter swing that occur at various frequencies, where: Period = 1/Frequency Period/mr = Period/(6.283*1000) Freq Period Period/mr mr/swing 8192. Hz 122.0 μsec 0.019 μsec/mr 10.5 mr/swing 512. 1953.0 0.31 0.62 64. 15.6 msec 2.5 0.08 8. 125.0 19.9 0.01 1. 1.0 sec 159.0 0.00125 0.125 8.0 1.3 msec/mr 0.00016 The above list shows the importance of accurate frequency adjustments for the acquisition of accurate high frequency phase measurements. The frequency match is obtained by performing a Frequency Adjustment as outlined in the section below. Typically, the frequency should be adjusted so that meter drift is less than one division over a 30 second interval. Drift rates of this magnitude yield phase drifts of less than one hundredth of the above values. XMT-G Manual Zonge International Page 9

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After the crystal ovens have heated for at least 60 minutes: (GDP-32 II Manual, Section 6.2) 1. Disconnect the Battery Charger. 2. Connect the synchronization cable between the I/O port on the transmitter controller XMT-32 and the TRANSMITTER I/O port on the Control I/O panel of the receiver (Figure 6.3.) 3. Switch the PHASE/BATT switch to the BATT position to check the transmitter controller battery voltage. The voltage should read at least 12.5 volts. If lower, there is either a poorly charged battery or a problem with the power system (GDP-32 II Manual, Section 15 - Maintenance.) 4. Switch the PHASE/BATT switch to the PHASE position. Observe the needle on the PHASE/BATT analog meter. Any needle movement indicates that there is some frequency difference between the GDP-32 II and the XMT-32 oscillators. The faster the needle is swinging, the greater the frequency difference. If there is absolutely no swinging over a period of a minute or so, the oscillators are either adjusted to the exact same frequency, or the oscillators are very different in frequency and the resultant beat frequency is beyond the response of the meter. Frequency adjustment and synchronization are accomplished with the GDP-32 II by executing the Synchronize to XMT function (Utilities Menu - Option 4.) 5. Follow the directions given on the screen. 6. While adjusting the frequency of either instrument, the needle should come to rest near the center of the meter, where it is most sensitive to movement. Use the cursor control keys to adjust the frequency up or down slightly until the needle roughly stabilizes near the center of the scale. 7. Press RESET to synchronize the counter chains of the two instruments. (When synchronizing multiple receivers proceed to step 12.) 8. Press CONTINUE. The GDP-32 II automatically measures the phase difference between the external calibration signal generated by the GDP-32 II and the corresponding signal generated by the XMT. If the two instruments have been properly synchronized, the measured phase difference is close to 0.0 mr. 9. Repeat step 8 several times to check the synchronization. The measured phase difference should remain close to 0.0 mr. 10. Ensure that synchronization can be maintained by disconnecting the synchronization cable and repeating the phase measurement. XMT-G Manual Zonge International Page 12

LOSING MANUAL SYNCHRONIZATION Synchronization can be lost in the following circumstances: Switching to GPS Sync Turning off power Losing battery power to either the transmitter controller or the receiver Re-adjusting the OSC TRIM pot on the transmitter controller Malfunction of the timing chain, crystal heater, crystal, timing boards, etc. The GDP or XMT receives a sharp jolt Synchronization is not lost in the following circumstances: Turning off the receiver using Utilities Menu Option 6 Turn Off Power. Re-booting the machine with the SHIFT/RESET sequence Changing frequencies Changing from time domain to frequency domain or vice versa. If synchronization is lost, connect the controller and the receiver using the synchronization cable and re-synchronize. In certain cases, such as in scalar CSAMT, you may be able to avoid this if you are interested only in phase difference between the electric and magnetic field components. Usually, loss of synchronization must be corrected immediately. XMT-G Manual Zonge International Page 13

XMT-G Specifications: Power consumption: 3.0 Watts @ 10-16VDC Endurance: approx 30h with standard 12V, 7.5Ah lead-acid battery; 15h with optional 802.11g wifi control. Calibration output: 3.3V, 20mA max, unipolar, synchronous to Period signal Absolute timing accuracy: < 100nS to global GPS UTC time base Cycle-Cycle Timing uncertainty: < 20nS Timing drift, GPS locked: to resolution of GPS constellation Timing drift, manual synchronization: < 1ppb GPS Antenna connection: 3.3-5V LNA power @ 100mA. Compatible with most external amplified L1 antennas, max cable length 10 meters with a Zonge approved antenna. XMT cable should match length of GDP cable to within 1m for best synchronization. XMT-G Manual Zonge International Page 14