"Razvan Popescu via groups.io" <yo8ryr@...> writes:
Hi,
I found partially my notes regarding E4413A that I had from a friend.
What I did was the following:
1) Before doing any EEPROM sensor operations run the following command
to stop the auto trigger from the power meter:
INIT:CONT OFF
2) Read the calibration table:
"DIAG:DET:EEPR? MemoryAddress,NumberOfBytesToRead"
Do not read more than 100 bytes, it will crash the power meter. In my
case an E4418B. Table size depends on how many frequency points were
calibrated. You can add additional points if you want for specific
frequencies like ham radio bands. There is enough space in the EEPROM.
Only the calibration table for the 26.5 GHz model was exactly 256
bytes.
H33 model will have it bigger.
Important thing to note is that the calibration table starts at 569
for E441XA sensors.
This is likely just coincidence because they are all calibrated by
keysight - it might be at any location in the EEPROM.
You can only write at specific locations based on the following
formula:
Start byte address in the EEPROM for each conversion entry is x*8+9
First 4 bytes are the frequency, next 2 bytes are the low CF and last
2 bytes are the high CF.
I will give an example below what will be the bytes values for a 50
MHz frequency and CF LOW 100% and CF HIGH 100%.
(0 * (2 ^ 24) + 0 * (2 ^ 16) + 195 * (2 ^ 8) + 80) / 1000 = 50 (MHz)
So if we consider that starting address is 569 for the E441XA sensors
you will need to write the following bytes at the address starting
569.
569 -> 0
570 -> 0
571 -> 195
572 -> 80
---- This will cover the 4 bytes for the frequency at 50 MHz ----
Now the next 2 bytes will be for the CF LOW:
100 * (64 * 256 + 0)/2^14 = 100 (CF LOW 100%)
573 -> 64
574 -> 0
Since the value for the CF HIGH is also 100 the same bytes will be
written to the addresses 575 and 576.
Without updating the checksum of the table the power meter will not
accept the new data... I attached a program i used to rewrite the
calibration data of my sensor. Keysight doesn't do any business with
private persons, so there was no other way i guess.
