Stucked on a trivial interpolation issue

options:
parameters:
author: ''
category: '[GRC Hier Blocks]'
cmake_opt: ''
comment: ''
copyright: ''
description: ''
gen_cmake: 'On'
gen_linking: dynamic
generate_options: qt_gui
hier_block_src_path: '.:'
id: test_interpolation
max_nouts: '0'
output_language: python
placement: (0,0)
qt_qss_theme: ''
realtime_scheduling: ''
run: 'True'
run_command: '{python} -u {filename}'
run_options: prompt
sizing_mode: fixed
thread_safe_setters: ''
title: test_interpolation
window_size: ''
states:
bus_sink: false
bus_source: false
bus_structure: null
coordinate: [8, 8]
rotation: 0
state: enabled

blocks:
- name: interpol
id: variable
parameters:
comment: ''
value: '3'
states:
bus_sink: false
bus_source: false
bus_structure: null
coordinate: [288, 12.0]
rotation: 0
state: enabled
- name: samp_rate
id: variable
parameters:
comment: ''
value: '32000'
states:
bus_sink: false
bus_source: false
bus_structure: null
coordinate: [184, 12]
rotation: 0
state: enabled
- name: analog_sig_source_x_0
id: analog_sig_source_x
parameters:
affinity: ''
alias: ''
amp: '2'
comment: ''
freq: '4000'
maxoutbuf: '0'
minoutbuf: '0'
offset: '-1'
phase: '0'
samp_rate: samp_rate
type: float
waveform: analog.GR_SQR_WAVE
states:
bus_sink: false
bus_source: false
bus_structure: null
coordinate: [88, 268.0]
rotation: 0
state: enabled
- name: analog_sig_source_x_0_0
id: analog_sig_source_x
parameters:
affinity: ''
alias: ''
amp: '2'
comment: ''
freq: '1000'
maxoutbuf: '0'
minoutbuf: '0'
offset: '-1'
phase: '0'
samp_rate: samp_rate
type: float
waveform: analog.GR_SIN_WAVE
states:
bus_sink: false
bus_source: false
bus_structure: null
coordinate: [88, 396.0]
rotation: 0
state: disabled
- name: blocks_throttle_0
id: blocks_throttle
parameters:
affinity: ''
alias: ''
comment: ''
ignoretag: 'True'
maxoutbuf: '0'
minoutbuf: '0'
samples_per_second: samp_rate*interpol
type: float
vlen: '1'
states:
bus_sink: false
bus_source: false
bus_structure: null
coordinate: [616, 404.0]
rotation: 0
state: true
- name: blocks_vector_source_x_0
id: blocks_vector_source_x
parameters:
affinity: ''
alias: ''
comment: ''
maxoutbuf: '0'
minoutbuf: '0'
repeat: 'True'
tags: ''
type: float
vector: '[1,0,1,0,1,0,1,1,0,1,0,0,0,1,1,0,1,0,0,0]'
vlen: '1'
states:
bus_sink: false
bus_source: false
bus_structure: null
coordinate: [88, 180.0]
rotation: 0
state: disabled
- name: interp_fir_filter_xxx_0_0
id: interp_fir_filter_xxx
parameters:
affinity: ''
alias: ''
comment: ''
interp: interpol
maxoutbuf: '0'
minoutbuf: '0'
samp_delay: '0'
taps: '1'
type: fff
states:
bus_sink: false
bus_source: false
bus_structure: null
coordinate: [344, 340.0]
rotation: 0
state: disabled
- name: qtgui_time_sink_x_0
id: qtgui_time_sink_x
parameters:
affinity: ''
alias: ''
alpha1: '1.0'
alpha10: '1.0'
alpha2: '1.0'
alpha3: '1.0'
alpha4: '1.0'
alpha5: '1.0'
alpha6: '1.0'
alpha7: '1.0'
alpha8: '1.0'
alpha9: '1.0'
autoscale: 'True'
axislabels: 'True'
color1: blue
color10: dark blue
color2: red
color3: green
color4: black
color5: cyan
color6: magenta
color7: yellow
color8: dark red
color9: dark green
comment: ''
ctrlpanel: 'False'
entags: 'True'
grid: 'True'
gui_hint: ''
label1: Signal 1
label10: Signal 10
label2: Signal 2
label3: Signal 3
label4: Signal 4
label5: Signal 5
label6: Signal 6
label7: Signal 7
label8: Signal 8
label9: Signal 9
legend: 'True'
marker1: '0'
marker10: '-1'
marker2: '1'
marker3: '-1'
marker4: '-1'
marker5: '-1'
marker6: '-1'
marker7: '-1'
marker8: '-1'
marker9: '-1'
name: Interpolated
nconnections: '1'
size: '64'
srate: samp_rate*interpol
stemplot: 'False'
style1: '1'
style10: '1'
style2: '1'
style3: '1'
style4: '1'
style5: '1'
style6: '1'
style7: '1'
style8: '1'
style9: '1'
tr_chan: '0'
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tr_level: '0.0'
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tr_slope: qtgui.TRIG_SLOPE_POS
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type: float
update_time: '0.10'
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width3: '1'
width4: '1'
width5: '1'
width6: '1'
width7: '1'
width8: '1'
width9: '1'
ylabel: Amplitude
ymax: '3'
ymin: '-3'
yunit: '""'
states:
bus_sink: false
bus_source: false
bus_structure: null
coordinate: [760, 292.0]
rotation: 0
state: true
- name: qtgui_time_sink_x_0_0
id: qtgui_time_sink_x
parameters:
affinity: ''
alias: ''
alpha1: '1.0'
alpha10: '1.0'
alpha2: '1.0'
alpha3: '1.0'
alpha4: '1.0'
alpha5: '1.0'
alpha6: '1.0'
alpha7: '1.0'
alpha8: '1.0'
alpha9: '1.0'
autoscale: 'False'
axislabels: 'True'
color1: blue
color10: dark blue
color2: red
color3: green
color4: black
color5: cyan
color6: magenta
color7: yellow
color8: dark red
color9: dark green
comment: ''
ctrlpanel: 'False'
entags: 'True'
grid: 'True'
gui_hint: ''
label1: Signal 1
label10: Signal 10
label2: Signal 2
label3: Signal 3
label4: Signal 4
label5: Signal 5
label6: Signal 6
label7: Signal 7
label8: Signal 8
label9: Signal 9
legend: 'True'
marker1: '0'
marker10: '-1'
marker2: '1'
marker3: '-1'
marker4: '-1'
marker5: '-1'
marker6: '-1'
marker7: '-1'
marker8: '-1'
marker9: '-1'
name: Source
nconnections: '1'
size: '64'
srate: samp_rate
stemplot: 'False'
style1: '1'
style10: '1'
style2: '1'
style3: '1'
style4: '1'
style5: '1'
style6: '1'
style7: '1'
style8: '1'
style9: '1'
tr_chan: '0'
tr_delay: '0'
tr_level: '0.0'
tr_mode: qtgui.TRIG_MODE_FREE
tr_slope: qtgui.TRIG_SLOPE_POS
tr_tag: '""'
type: float
update_time: '0.10'
width1: '1'
width10: '1'
width2: '1'
width3: '1'
width4: '1'
width5: '1'
width6: '1'
width7: '1'
width8: '1'
width9: '1'
ylabel: Amplitude
ymax: '3'
ymin: '-3'
yunit: '""'
states:
bus_sink: false
bus_source: false
bus_structure: null
coordinate: [624, 172.0]
rotation: 0
state: true
- name: rational_resampler_xxx_0
id: rational_resampler_xxx
parameters:
affinity: ''
alias: ''
comment: ''
decim: '1'
fbw: '0'
interp: interpol
maxoutbuf: '0'
minoutbuf: '0'
taps: '1'
type: fff
states:
bus_sink: false
bus_source: false
bus_structure: null
coordinate: [344, 404.0]
rotation: 0
state: true

connections:
- [analog_sig_source_x_0, '0', interp_fir_filter_xxx_0_0, '0']
- [analog_sig_source_x_0, '0', qtgui_time_sink_x_0_0, '0']
- [analog_sig_source_x_0, '0', rational_resampler_xxx_0, '0']
- [analog_sig_source_x_0_0, '0', interp_fir_filter_xxx_0_0, '0']
- [analog_sig_source_x_0_0, '0', qtgui_time_sink_x_0_0, '0']
- [analog_sig_source_x_0_0, '0', rational_resampler_xxx_0, '0']
- [blocks_throttle_0, '0', qtgui_time_sink_x_0, '0']
- [blocks_vector_source_x_0, '0', interp_fir_filter_xxx_0_0, '0']
- [blocks_vector_source_x_0, '0', qtgui_time_sink_x_0_0, '0']
- [blocks_vector_source_x_0, '0', rational_resampler_xxx_0, '0']
- [interp_fir_filter_xxx_0_0, '0', blocks_throttle_0, '0']
- [rational_resampler_xxx_0, '0', blocks_throttle_0, '0']

metadata:
file_format: 1

Hi

I'm stucked on a trivial interpolation problem.

I was trying to interpolate a binary source ( in the attached flowgraph I've witched to a rectangular wave source to analyse and explain my problem).

• So I've a rectangular source with 4 sample/period : 1 1 1 1 -1 -1 -1-1 1... .
• I interpolate whith a 3 interpolation factor
• I was guessiong to obtain : 1 1 1 / 1 1 1 / 1 1 1 / 1 1 1 / -1 -1 -1/ -1 -1 -1/ -1 -1 -1/ ...(/ used to separate group of 3 samples)
  
• Instead I get: 1 0 0 / 1 0 0 /1 0 0 /1 0 0 /-1 0 0 /-1 0 0 /-1 0 0 /-1 0 0 /

This seems wrong as compared to paragraph "E2.3. A Note on Resampling" on this GNURadio Wiki  tutorial

Does I made something wrong, or Does I've been infected by Covid19.

Sincerely,

Christophe confined at home since 7 days (North of France)