Difference between revisions of "BG7TBL"

**BG7TBL**
Status	planned
Frequency (user)	138MHz-4.4GHz
Waveforms	sine (fixed)
Amplitude	? V
Connectivity	USB

Latest revision as of 13:13, 21 May 2018

The BG7TBL USB RF Signal Generator is a PC-based function generator. It has no external controls, requiring a USB connection to a computer.

Software to run this hardware can be found here http://www.dl4jal.eu/.

This device can be bought on ebay for ca $65. Search for "138MHz-4.4GHz". There is a version with the ADF4351 instead that will give you more range (35MHz-4.4GHz).

Hardware

Microcontroller: Atmel Atmega 8L
Wideband Synthesizer: ADF4350
USB to Serial: FTDI FT232RL
Logarithmic Amplifier AD8307
Mixer: IAM 81008
LDO: AMS1117

Photos

Protocol

Baud 57600, 8n1

The protocol is binary serial based.

Query firmware

Send 0x8f+"v"

The answer should be in hex:

77

Where the returned byte is the firmware version, 0x77 = 119 = 'w'.

#!/usr/bin/python                             

import serial

ser = serial.Serial('/dev/ttyUSB0', 57600, timeout=1) # Linux first FTDI
ser.write("\x8f" + "v")
print("version is " + ser.read())

Signal generator

Setting frequency

To set a frequency send:

0x8f

Then f and then the frequency divided by 10 with leading zeroes. For example this is the payload for 400MHz.

400 000 000 / 10
f040000000

#!/usr/bin/python
import sys, serial

ser = serial.Serial('/dev/ttyUSB0', 57600, timeout=1) # Linux first FTDI
# sys.argv[1] is frequency in Herz
cmd = "\x8f" + "f" + '{:09d}'.format(int(sys.argv[1])/10)
ser.write(cmd)

Spectrum analyzer

The protocol is briefly described in the source code here:

https://github.com/DoYouKnow/BG7TBL_Reader

Here is a minimal code for an 'x' sweep (the protocol is described in chapter 6 of http://www.dl4jal.eu/LinNWT_doc_en.pdf ). The device sends back the expected number of bytes but it seems I have to divide the frequency by 10... (?).

#!/usr/bin/python
import sys, serial, struct

start_frequency = 100000000    # FM band
increment       = 20000
steps           = 2000
#
# 'x' sweep (writing the command returns (4 * steps) bytes (what is it, I don't know)
#
cmd = "\x8f" + "x" + '{:09d}{:08d}{:04d}'.format(start_frequency/10, increment, steps)
ser = serial.Serial('/dev/ttyUSB0', 57600, timeout=100) # Linux first FTDI
ser.write(cmd)
rsp = ser.read(4 * steps)
if len(rsp) < (4 * steps):
	sys.stderr.write("Warning : Did not read enough measures! Try increasing the timeout\n")
	steps = len(rsp)/4    # adapt to the number of measures read
val_tab = struct.unpack_from("<" + "h"*2*steps, rsp) # 2 * steps 'little endian shorts'
for i in range(0, steps):
	print(val_tab[2*i])	# channel A (A and B are interleaved)

@@ Line 1: / Line 1: @@
 {{Infobox signal generator
-| image = [[File:NWT4000_case.jpg|180px]]
+| image = [[File:BG7TBL_case.jpg|180px]]
-| name = NWT4000
+| name = BG7TBL
 | status = planned
 | source_code_dir =
@@ Line 18: / Line 18: @@
 * Microcontroller: [http://www.atmel.com/Images/Atmel-2486-8-bit-AVR-microcontroller-ATmega8_L_datasheet.pdf Atmel Atmega 8L]
 * Wideband Synthesizer: [http://www.analog.com/media/en/technical-documentation/data-sheets/ADF4350.pdf ADF4350]
-* USB to Serial: FTDI FT232RL
+* USB to Serial: [http://www.ftdichip.com/Support/Documents/DataSheets/ICs/DS_FT232R.pdf FTDI FT232RL]
 * Logarithmic Amplifier [http://www.analog.com/media/en/technical-documentation/data-sheets/AD8307.pdf AD8307]
 * Mixer: [http://www.qsl.net/n9zia/omnitracs/IAM81008.pdf IAM 81008]
@@ Line 26: / Line 26: @@
 <gallery>
-NWT4000 pcb top.jpg
+BG7TBL pcb top.jpg
-NWT4000 pcb bot.jpg
+BG7TBL pcb bot.jpg
 </gallery>
 == Protocol ==
+Baud 57600, 8n1
-The protocol is a serial protocol, send an f and the frequency divided by 10 to set the output to the desired frequency.
+The protocol is binary serial based.
+=== Query firmware ===
+* Send 0x8f+"v"
+The answer should be in hex:
+* 77
+Where the returned byte is the firmware version, 0x77 = 119 = 'w'.
+<pre>
+#!/usr/bin/python
+import serial
+ser = serial.Serial('/dev/ttyUSB0', 57600, timeout=1) # Linux first FTDI
+ser.write("\x8f" + "v")
+print("version is " + ser.read())
+</pre>
+=== Signal generator ===
+==== Setting frequency ====
+To set a frequency send:
+* 0x8f
+Then f and then the frequency divided by 10 with leading zeroes. For example this is the payload for 400MHz.
+* 400 000 000 / 10
+* f040000000
+<pre>
+#!/usr/bin/python
+import sys, serial
+ser = serial.Serial('/dev/ttyUSB0', 57600, timeout=1) # Linux first FTDI
+# sys.argv[1] is frequency in Herz
+cmd = "\x8f" + "f" + '{:09d}'.format(int(sys.argv[1])/10)
+ser.write(cmd)
+</pre>
+=== Spectrum analyzer ===
+The protocol is briefly described in the source code here:
+https://github.com/DoYouKnow/BG7TBL_Reader
+Here is a minimal code for an 'x' sweep <small>(the protocol is described in chapter 6 of http://www.dl4jal.eu/LinNWT_doc_en.pdf )</small>.  The device sends back the expected number of bytes but it seems I have to divide the frequency by 10... (?).
+<pre>
+#!/usr/bin/python
+import sys, serial, struct
+start_frequency = 100000000    # FM band
+increment       = 20000
+steps           = 2000
+#
+# 'x' sweep (writing the command returns (4 * steps) bytes (what is it, I don't know)
+#
+cmd = "\x8f" + "x" + '{:09d}{:08d}{:04d}'.format(start_frequency/10, increment, steps)
+ser = serial.Serial('/dev/ttyUSB0', 57600, timeout=100) # Linux first FTDI
+ser.write(cmd)
+rsp = ser.read(4 * steps)
+if len(rsp) < (4 * steps):
+	sys.stderr.write("Warning : Did not read enough measures! Try increasing the timeout\n")
+	steps = len(rsp)/4    # adapt to the number of measures read
+val_tab = struct.unpack_from("<" + "h"*2*steps, rsp) # 2 * steps 'little endian shorts'
+for i in range(0, steps):
+	print(val_tab[2*i])	# channel A (A and B are interleaved)
+</pre>