From 84d6e5003fb26ae15556f1fc8792653db22b6ceb Mon Sep 17 00:00:00 2001
From: Vlad N <v neg nev at gee mail dot com>
Date: Mon, 20 Jun 2022 23:14:17 +0200
Subject: [PATCH] Basic noise/jitter test script
---
readme.org | 8 ++---
test_noise.py | 89 +++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 92 insertions(+), 5 deletions(-)
create mode 100644 test_noise.py
diff --git a/readme.org b/readme.org
index 07cd718..bdbd348 100644
--- a/readme.org
+++ b/readme.org
@@ -1,6 +1,6 @@
#+TITLE: marcos_client
-(NEED TO UPDATE THIS FILE)
+(NEED TO UPDATE THIS FILE -- SOME OF THE DESCRIPTIONS ARE OBSOLETE)
Python-based MaRCoS GUI and associated tests.
@@ -11,14 +11,12 @@ See the [[https://github.com/vnegnev/marcos_extras/wiki][MaRCoS wiki]] for info;
- Install =msgpack= for Python manually or via the package manager of your choice.
- Clone the repo and copy =local_config.py.example= to =local_config.py=.
-
+
- Edit =local_config.py= to suit your network and hardware setup.
- Run =test_server.py= and make sure no errors are returned.
- - Run =test_acquire.py= to test the hardware in a basic acquisition.
-
- - Run =test_experiment.py= to test the experiment API.
+ - Run =test_noise.py= to generate some simple pulses and view their properties on an oscilloscope.
- Import experiment.py in your higher-level MRI scripts.
diff --git a/test_noise.py b/test_noise.py
new file mode 100644
index 0000000..f13a085
--- /dev/null
+++ b/test_noise.py
@@ -0,0 +1,89 @@
+#!/usr/bin/env python3
+
+import numpy as np
+import matplotlib.pyplot as plt
+import experiment as ex
+from local_config import grad_board
+
+import pdb
+st = pdb.set_trace
+
+def test_jitter(
+ rf_pulse_freq = 2, # MHz
+ rf_pulse_start_time = 10, # us
+ rf_pulse_length = 2, # us
+ rf_amp=0.8, # fraction of full-scale
+ rf_interval=5, # us, delay between start of first and start of
+ # second pulse - must be bigger than pulse
+ # length
+ grad_pulse_start_time = 10, # us
+ grad_pulse_length = 40, # us
+ grad_interval=80, # us
+ grad_amp=0.2, # fraction of full-scale
+ loops=10,
+ print_loops=False,
+ plot_sequence=False,
+ experiment_kwargs={}):
+ """Two successive pulses, with an adjustable interval between them.
+
+ Trigger an oscilloscope from the TX gate or first pulse, and look
+ at the second pulse, with a suitable hold-off time so that
+ triggering is reliable. Over many repetitions, the timing jitter
+ will be visible.
+ """
+ tx_gate_start_time = 0
+ tx_gate_length = 0.1
+
+ rf_data = (
+ rf_pulse_start_time + np.array([0, rf_pulse_length, rf_interval, rf_pulse_length + rf_interval]),
+ np.array([rf_amp, 0, rf_amp, 0])
+ )
+
+ grad_data = (
+ grad_pulse_start_time + np.array([0, grad_pulse_length, grad_interval, grad_pulse_length + grad_interval]),
+ np.array([grad_amp, 0, grad_amp, 0])
+ )
+
+ gpa_fhdo_offset_time = 10 if grad_board == "gpa-fhdo" else 0
+
+ event_dict = {'tx0': rf_data,
+ 'tx1': rf_data,
+ 'grad_vx': grad_data,
+ 'grad_vy': grad_data,
+ 'grad_vz': grad_data,
+ 'grad_vz2': grad_data,
+ 'tx_gate': (tx_gate_start_time + np.array([0, tx_gate_length]), np.array([1, 0]))}
+
+ exp = ex.Experiment(lo_freq=rf_pulse_freq, gpa_fhdo_offset_time=gpa_fhdo_offset_time, **experiment_kwargs)
+ exp.add_flodict(event_dict)
+
+ if plot_sequence:
+ exp.plot_sequence()
+ plt.show()
+
+ for k in range(loops):
+ exp.run()
+ if print_loops and k % 1000 == 0:
+ print(f"Loop {k}")
+
+ exp.close_server(only_if_sim=True)
+
+if __name__ == "__main__":
+ # slowed down to suit VN's setup, due to GPA-FHDO communication chip being dead
+ experiment_kwargs = {'init_gpa': True, 'grad_max_update_rate': 0.1}
+ loops = int(1e6)
+
+ # Enable the test that you want to run below
+
+ # RF pulses close together, gradient pulses further apart, rf and grad start simultaneously (default)
+ if False:
+ test_jitter(loops=loops, experiment_kwargs=experiment_kwargs) # many loops
+
+ # RF and gradient pulses start almost simultaneously (RF offset to avoid SPI noise), second pulses happen at an adjustable interval
+ if True:
+ interval=100000 # 100ms
+ amp = 0.2
+ test_jitter(loops=loops, rf_pulse_start_time=10.5,
+ rf_interval=interval, rf_amp=amp,
+ grad_interval=interval, grad_amp=amp,
+ experiment_kwargs=experiment_kwargs) # many loops
--
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