2.1 TX Test Modes

The ATA8352 device transmits short FM-modulated pulses in the range of 1 to 10 ns duration with a typical FM deviation m of +/-125 MHz. The center frequencies f0 are typically 6.520 GHz, 7.04 GHz, 7.56 GHz and 7.987 GHz. The default center frequency is set to 6.52 GHz. With the default setting, the figure below shows these parameters:
  • f0 center frequency = 6.52 GHz
  • m frequency deviation = 125 MHz
  • n pulse bandwidth = 250 MHz
  • bw signal bandwidth = 500 MHz
    Figure 2-1. TX Output Spectrum
The repetition rate, ti, of these pulses is 253 ns (default) with a width, dt, of 4.5 ns, as shown in following figure:
Figure 2-2. Symbol Pulse Train
The TX Test mode is set up using register A21 (GPO test register) with the following settings:
Table 2-1. A21 Register Configuration Settings
Bit#NameDescription
20DIG_TX_OnlyPreamble

1 = Transmit only preamble continuously

(Test mode, to exit this mode a power-down sequence must be applied)

19DIG_TX_Pattern[2]select pre-amble pattern:
  • 0 = 00001111
  • 1 = 0001
  • 3 = 0111
  • 4 = 0101
  • 5 = 0000
  • 6 = 1111
18DIG_TX_Pattern[1]
17DIG_TX_Pattern[0]

The following settings are used for testing purposes:

  1. DIG_TX_Pattern[2:0] = 100 to transmit the frequencies f0-m and f0+m in an alternating order
  2. DIG_TX_Pattern[2:0] = 101 to transmit the frequency f0+m
  3. DIG_TX_Pattern[2:0] = 110 to transmit the frequencies f0-m

The following figures illustrate the TX spectrum without the filter and antenna in the RF path and with the conducted measurement.

The spectrum analyzer uses the following settings:

  • Center frequency: 6.52 GHz
  • Span: 1 GHz
  • Trace mode: Maximum hold
  • Resolution Bandwidth (RBW) and Video Bandwidth (VBW): 3 MHz
  • Sweep time: 6 ms RBW
This TX Test mode generates a spectrum (see the following figure) for the pattern DIG_TX_Pattern[2:0] = 100 for both modulation frequencies.
Figure 2-3. TX Spectrum for f0-m and f0+m
The following figure shows the spectrum for the pattern DIG_TX_Pattern[2:0] = 101 for the upper modulation frequency.
Figure 2-4. TX Spectrum for f0+m
The following figure shows the spectrum for the pattern DIG_TX_Pattern[2:0] = 110 for the lower modulation frequency.
Figure 2-5. TX Spectrum for f0-m
Set the A19 register (digital control register) in the TX mode with the following settings to activate the TX Test mode.
Table 2-2. A19 Register Configuration Settings
Bit#Name Description
24DIG_RXPR_TXVR0 = start with TX state first
23DIG_RXoRXPR_enable0 = disable (default)
22DIG_XoX_PRVR
  • Select for TX/VR modes:
    • 1 = Write operation to data FIFO triggers TX mode
    • 0 = Bit DIG_RXPR_TXVR triggers VR mode
  • Select for RX/PR modes:
    • 1 = Received data written into A18 in RX mode
    • 0 = Received data written into A18 in PR mode
All other register bits for registers A21 and A19 remain as default values. Writing the register A19 of the device starts the TX Test mode. Apply a power-down sequence on the device to exit the TX Test mode. For more details on these A21 and A19 registers, refer to the ATA8352 Impulse-Radio Ultra-Wideband (IR-UWB) Transceiver User’s Guide (DS50003125).