Author: Ed

Satellite Dish Mounting Angle in Norway

A friend asked why Norwegians point their satellite dishes at the ground. After maneuvering Google Streetview around Vadsø for a while, I found a dish in profile:

TV satellite dish – Vadso Norway

Turns out geostationary orbit is way low, as seen from the top of the world. A bit of doodling shows it’s only 11° above the horizon at 70° N:

TV Satellite Dish – Horizon Angle at 70° N

TV satellite antennas have an offset-fed reflector, with the receiver in the lump at the end of the spine sticking out from the bottom of the dish, so as to not obstruct the signal entering the dish. Even though the plane of the reflector points downward, the signal reflected to the receiver comes in from above.

Ain’t ~~science~~ trigonometry grand?

2016-10-22

Raspberry Pi Streaming Radio Player: Improved Pipe Handling

My Raspberry Pi-based streaming radio player generally worked fine, except sometimes the keypad / volume control knob would stop responding after switching streams. This being an erratic thing, the error had to be a timing problem in otherwise correct code and, after spending Quality Time with the Python subprocess and select doc, I decided I was abusing mplayer’s stdin and stdout pipes.

This iteration registers mplayer’s stdout pipe as Yet Another select.poll() Polling Object, so that the main loop can respond whenever a complete line arrives. Starting mplayer in quiet mode reduces the tonnage of stdout text, at the cost of losing the streaming status that I really couldn’t do anything with, and eliminates the occasional stalls when mplayer (apparently) dies in the middle of a line.

The code kills and restarts mplayer whenever it detects an EOF or stream cutoff. That works most of the time, but a persistent server or network failure can still send the code into a sulk. Manually selecting a different stream (after we eventually notice the silence) generally sets things right, mainly by whacking mplayer upside the head; it’s good enough.

It seems I inadvertently invented streaming ad suppression by muting (most of) the tracks that produced weird audio effects. Given that the “radio stations” still get paid for sending ads to me, I’m not actually cheating anybody out of their revenue: I’ve just automated our trips to the volume control knob. The audio goes silent for a few seconds (or, sheesh, a few minutes) , blatting a second or two of ad noise around the gap to remind us of what we’re missing; given the prevalence of National Forest Service PSAs, the audio ad market must be a horrific wasteland.

The Python source code as a GitHub Gist:

	from evdev import InputDevice,ecodes,KeyEvent
	import subprocess32 as subp
	import select
	import re
	import sys
	import time
	import logging

	Media = {'KEY_KP7' : ['Classical',False,['mplayer','–quiet','-playlist','http://stream2137.init7.net/listen.pls'%5D%5D,
	'KEY_KP8' : ['Jazz',False,['mplayer','–quiet','-playlist','http://stream2138.init7.net/listen.pls'%5D%5D,
	'KEY_KP9' : ['WMHT',False,['mplayer','–quiet','http://live.str3am.com:2070/wmht1'%5D%5D,
	'KEY_KP4' : ['Classic 1000',True,['mplayer','–quiet','-playlist','http://listen.radionomy.com/1000classicalhits.m3u'%5D%5D,
	'KEY_KP5' : ['DCNY 911',False,['mplayer','–quiet','-playlist','http://www.broadcastify.com/scripts/playlists/1/12305/-5857889408.m3u'%5D%5D,
	'KEY_KP6' : ['WAMC',False,['mplayer','–quiet','http://pubint.ic.llnwd.net/stream/pubint_wamc'%5D%5D,
	'KEY_KP1' : ['60s',True,['mplayer','–quiet','-playlist','http://listen.radionomy.com/all60sallthetime-keepfreemusiccom.m3u'%5D%5D,
	'KEY_KP2' : ['50-70s',True,['mplayer','–quiet','-playlist','http://listen.radionomy.com/golden-50-70s-hits.m3u'%5D%5D,
	'KEY_KP3' : ['Soft Rock',True,['mplayer','–quiet','-playlist','http://listen.radionomy.com/softrockradio.m3u'%5D%5D,
	'KEY_KP0' : ['Zen',True,['mplayer','–quiet','-playlist','http://listen.radionomy.com/zen-for-you.m3u'%5D%5D
	}

	CurrentKC = 'KEY_KP3'

	Controls = {'KEY_KPSLASH' : '//////',
	'KEY_KPASTERISK' : '******',
	'KEY_KPENTER' : ' ',
	'KEY_KPMINUS' : '<',
	'KEY_KPPLUS' : '>',
	'KEY_VOLUMEUP' : '*',
	'KEY_VOLUMEDOWN' : '/'
	}

	MuteStrings = ["TargetSpot","[Unknown]","Advert:","+++","—","SRR","Srr","ZEN FOR"]

	MuteDelay = 8.0 # delay before non-music track; varies with buffering
	UnMuteDelay = 7.5 # delay after non-music track
	Muted = False # keep track of muted state

	MixerChannel = 'PCM' # which amixer thing to use

	logging.basicConfig(format='%(asctime)s %(levelname)s:%(message)s',filename='/tmp/Streamer.log',level=logging.INFO)
	logger = logging.getLogger()

	# set up event inputs and polling objects
	# This requires some udev magic to create the symlinks

	k = InputDevice('/dev/input/keypad')
	k.grab()

	kp = select.poll()
	kp.register(k.fileno(),select.POLLIN + select.POLLPRI + select.POLLERR)

	v = InputDevice('/dev/input/volume')
	v.grab()

	vp = select.poll()
	vp.register(v.fileno(),select.POLLIN + select.POLLPRI + select.POLLERR)

	# set up file for output tracing

	lw = open('/tmp/mp.log','w') # mplayer piped output

	# set the mixer output low enough that the initial stream won't wake the dead

	subp.call(['amixer','sset',MixerChannel,'10'])

	# Start the player with the default stream, set up for polling

	print 'Starting mplayer on',Media[CurrentKC][0],' -> ',Media[CurrentKC][-1][-1]
	logging.info('Starting mplayer on %s -> %s',Media[CurrentKC][0],Media[CurrentKC][-1][-1])
	p = subp.Popen(Media[CurrentKC][-1],
	stdin=subp.PIPE,stdout=subp.PIPE,stderr=subp.STDOUT)

	pp = select.poll() # this may be valid for other invocations, but is not pretty
	pp.register(p.stdout.fileno(),select.POLLIN + select.POLLPRI + select.POLLERR)

	print ' … running'

	#——————–
	#— Play the streams

	while True:

	# pluck next line from mplayer and decode it

	if [] != pp.poll(10):
	text = p.stdout.readline()

	if 'ICY Info: ' in text: # these lines may contain track names
	lw.write(text)
	lw.flush()

	trkinfo = text.split(';') # also splits at semicolon embedded in track name
	# logging.info('Raw split line: %s', trkinfo)
	for ln in trkinfo:
	if 'StreamTitle' in ln: # this part contains a track name
	NeedMute = False # assume a listenable track
	if 2 == ln.count("'"): # exactly two single quotes = probably none embedded in track name
	trkhit = re.search(r"StreamTitle='(.*)'",ln)
	if trkhit: # true for valid search results
	TrackName = trkhit.group(1) # the string between the two quotes
	print 'Track name: ', TrackName
	logging.info('Track name: [%s]', TrackName)
	if Media[CurrentKC][1] and ( (len(TrackName) == 0) or any(m in TrackName for m in MuteStrings) ) :
	NeedMute = True
	else:
	print ' … semicolon in track name: ', ln
	logging.info('Semicolon in track name: [' + ln + ']')
	else:
	print ' … quotes in track name: ', ln
	logging.info('Quotes in track name: [' + ln + ']')
	if NeedMute:
	print ' … muting:',
	if Media[CurrentKC][1] and not Muted:
	time.sleep(MuteDelay) # brute-force assumption about buffer leadtime
	subp.call(['amixer','-q','sset',MixerChannel,'mute'])
	Muted = True
	print 'done'
	logging.info('Track muted')
	else:
	print ' … unmuting:',
	if Muted:
	if Media[CurrentKC][1]:
	time.sleep(UnMuteDelay) # another brute-force timing assumption
	Muted = False
	subp.call(['amixer','-q','sset',MixerChannel,'unmute'])
	print 'done'
	logging.info('Track unmuted')

	elif 'Exiting.' in text: # mplayer just imploded
	lw.write(text)
	lw.flush()
	print 'Got EOF / stream cutoff'
	logging.info('EOF or stream cutoff')
	print ' … killing dead mplayer'
	pp.unregister(p.stdout.fileno())
	p.terminate() # p.kill()
	p.wait()
	# print ' … flushing pipes'
	# lw.truncate(0)
	print ' … discarding keys'
	while [] != kp.poll(0):
	kev = k.read
	print ' … restarting mplayer: ',Media[CurrentKC][0]
	logging.info('Restarting mplayer')
	p = subp.Popen(Media[CurrentKC][-1],
	stdin=subp.PIPE,stdout=subp.PIPE,stderr=subp.STDOUT)
	pp.register(p.stdout.fileno(),select.POLLIN + select.POLLPRI + select.POLLERR)
	print ' … running'
	logging.info(' … running')


	# accept pending events from volume control knob

	if [] != vp.poll(10):
	vev = v.read()
	lw.write('Volume')
	lw.flush()
	for e in vev:
	if e.type == ecodes.EV_KEY:
	kc = KeyEvent(e).keycode

	# print 'Volume kc: ',kc

	if kc in Controls:
	print 'Vol Control: ',kc
	try:
	p.stdin.write(Controls[kc])
	except Exception as e:
	print "Can't send control: ",e
	print ' … restarting player: ',Media[CurrentKC][0]
	logging.info('Error sending volume, restarting player')
	pp.unregister(p.stdout.fileno())
	p = subp.Popen(Media[CurrentKC][-1],
	stdin=subp.PIPE,stdout=subp.PIPE,stderr=subp.STDOUT)
	pp.register(p.stdout.fileno(),select.POLLIN + select.POLLPRI + select.POLLERR)
	print ' … running'
	logging.info(' … running')


	# accept pending events from keypad

	if [] != kp.poll(10):
	kev = k.read()
	lw.write("Keypad")
	lw.flush()
	for e in kev:
	if e.type == ecodes.EV_KEY:
	kc = KeyEvent(e).keycode

	if kc == 'KEY_NUMLOCK': # discard these, as we don't care
	continue

	# print 'Got: ',kc

	if (kc == 'KEY_BACKSPACE') and (KeyEvent(e).keystate == KeyEvent.key_hold):
	if True:
	print 'Backspace = shutdown!'
	p.kill()
	logging.shutdown()
	q = subp.call(['sudo','shutdown','-P','now'])
	q.wait()
	time.sleep(5)
	print "Oddly, we did not die…"
	else:
	print 'BS = bail from main!'
	logging.shutdown()
	sys.exit(0)
	break

	if KeyEvent(e).keystate != KeyEvent.key_down: # discard key up & other rubbish
	continue

	if kc in Controls:
	print 'Control:', kc
	try:
	p.stdin.write(Controls[kc])
	except Exception as e:
	print "Can't send control: ",e
	print ' … restarting player: ',Media[CurrentKC][0]
	logging.info('Error sending controls, restarting player')
	pp.unregister(p.stdout.fileno())
	p.terminate() # p.kill()
	p.wait()
	p = subp.Popen(Media[CurrentKC][-1],
	stdin=subp.PIPE,stdout=subp.PIPE,stderr=subp.STDOUT)
	pp.register(p.stdout.fileno(),select.POLLIN + select.POLLPRI + select.POLLERR)
	print ' … running'
	logging.info(' … running')

	if kc in Media:
	print 'Switching stream to ',Media[kc][0],' -> ',Media[kc][-1][-1]
	logging.info('Switching stream: ' + Media[kc][0] + ' -> ' + Media[kc][-1][-1])
	CurrentKC = kc
	print ' … halting player'
	try:
	p.communicate(input='q')
	except Exception as e:
	print 'Perhaps mplayer died?',e
	print ' … killing it for sure'
	pp.unregister(p.stdout.fileno())
	p.terminate() # p.kill()
	p.wait()
	# print ' … flushing pipes'
	# lw.truncate(0)
	print ' … restarting player: ',Media[CurrentKC][0]
	p = subp.Popen(Media[CurrentKC][-1],
	stdin=subp.PIPE,stdout=subp.PIPE,stderr=subp.STDOUT)
	pp.register(p.stdout.fileno(),select.POLLIN + select.POLLPRI + select.POLLERR)
	print ' … running'
	logging.info(' … running')

	print 'Out of loop!'
	logging.shutdown()

view raw Streamer.py hosted with ❤ by GitHub

2016-10-21

HP 7475A Plotter: Coordinate Pruning

The original SuperFormula equation produces points in polar coordinates, which the Chiplotle library converts to the rectilinear format more useful with Cartesian plotters. I’ve been feeding the equation with 10001 angular values (10 passes around the paper, with 1000 points per pass, plus one more point to close the pattern), which means the angle changes by 3600°/10000 = 0.36° per point. Depending on the formula’s randomly chosen parameters, each successive point can move the plotter pen by almost nothing to several inches.

On the “almost nothing” end of the scale, the plotter slows to a crawl while the serial interface struggles to feed the commands. Given that you can’t see the result, why send the commands?

Computing point-to-point distances goes more easily in rectilinear coordinates, so I un-tweaked my polar-modified superformula function to return the points in rectangular coordinates. I’d originally thought a progressive scaling factor would be interesting, but it never happened.

The coordinate pruning occurs in the supershape function, which now contains a loop to scan through the incoming list of points from the superformula function and add a point to the output path only when it differs by enough from the most recently output point:

    path = []
    path.append(Coordinate(width * points[0][0], height * points[0][1]))
    outi = 0
    xp, yp = points[outi][0], points[outi][1]
    for i in range(len(points))[1:]:
        x,y = width * points[i][0], height * points[i][1]
        dist = sqrt(pow(x - xp,2) + pow(y - yp,2))
        if dist > 60 :
          path.append(Coordinate(x, y))
          outi = i
          xp, yp = x, y

    path.append(Coordinate(width * points[-1][0], height * points[-1][1]))
    print "Pruned",len(points),"to",len(path),"points"

The first and last points always go into the output list; the latter might be duplicated, but that doesn’t matter.

Note that you can’t prune the list by comparing successive points, because then you’d jump directly from the start of a series of small motions to their end. The idea is to step through the small motions in larger units that, with a bit of luck, won’t be too ugly.

The width and height values scale the XY coordinates to fill either A or B paper sheets, with units of “Plotter Units” = 40.2 PU/mm = 1021 PU/inch. You can scale those in various ways to fit various output sizes within the sheets, but I use the defaults that fill the entire sheets with a reasonable margin. As a result, the magic number 60 specifies 60 Plotter Units; obviously, it should have a suitable name.

Pruning to 40 PU = 1.0 mm (clicky for more dots, festooned with over-compressed JPEG artifacts):

Pruning to 60 PU = 1.5 mm:

Pruning to 80 PU = 2.0 mm:

Pruning to 120 PU = 3.0 mm:

All four of those plots have the same pens in the same order, although I refilled a few of them in flight.

By and large, up through 80 PU there’s not much visual difference, although you can definitely see the 3 mm increments at 120 PU. However, the plotting time drops from just under an hour for each un-pruned plot to maybe 15 minutes with 120 PU pruning, with 60 PU producing very good results at half an hour.

Comparing the length of the input point lists to the pruned output path lists, including some pruning values not shown above:

Prune 20
1 - m: 5.3, n1: 0.15, n2=n3: 0.80
Pruned 10001 to 4856 points
2 - m: 5.3, n1: 0.23, n2=n3: 0.75
Pruned 10001 to 5545 points
3 - m: 5.3, n1: 1.15, n2=n3: 0.44
Pruned 10001 to 6218 points
4 - m: 5.3, n1: 0.41, n2=n3: 1.50
Pruned 10001 to 7669 points
5 - m: 5.3, n1: 0.29, n2=n3: 0.95
Pruned 10001 to 6636 points
6 - m: 5.3, n1: 0.95, n2=n3: 0.16
Pruned 10001 to 5076 points

Prune 40
1 - m: 3.1, n1: 0.23, n2=n3: 0.26
Pruned 10001 to 2125 points
2 - m: 3.1, n1: 1.05, n2=n3: 0.44
Pruned 10001 to 5725 points
3 - m: 3.1, n1: 0.25, n2=n3: 0.32
Pruned 10001 to 2678 points
4 - m: 3.1, n1: 0.43, n2=n3: 0.34
Pruned 10001 to 4040 points
5 - m: 3.1, n1: 0.80, n2=n3: 0.40
Pruned 10001 to 5380 points
6 - m: 3.1, n1: 0.55, n2=n3: 0.56
Pruned 10001 to 5424 points

Prune 60
1 - m: 1.1, n1: 0.45, n2=n3: 0.40
Pruned 10001 to 2663 points
2 - m: 1.1, n1: 0.41, n2=n3: 0.14
Pruned 10001 to 1706 points
3 - m: 1.1, n1: 1.20, n2=n3: 0.75
Pruned 10001 to 4446 points
4 - m: 1.1, n1: 0.33, n2=n3: 0.80
Pruned 10001 to 3036 points
5 - m: 1.1, n1: 0.90, n2=n3: 1.40
Pruned 10001 to 4723 points
6 - m: 1.1, n1: 0.61, n2=n3: 0.65
Pruned 10001 to 3601 points

Prune 80
1 - m: 3.7, n1: 0.95, n2=n3: 0.58
Pruned 10001 to 3688 points
2 - m: 3.7, n1: 0.49, n2=n3: 0.22
Pruned 10001 to 2258 points
3 - m: 3.7, n1: 0.57, n2=n3: 0.90
Pruned 10001 to 3823 points
4 - m: 3.7, n1: 0.25, n2=n3: 0.40
Pruned 10001 to 2161 points
5 - m: 3.7, n1: 0.47, n2=n3: 0.30
Pruned 10001 to 2532 points
6 - m: 3.7, n1: 0.45, n2=n3: 0.14
Pruned 10001 to 1782 points

Prune 120
1 - m: 1.9, n1: 0.33, n2=n3: 0.48
Pruned 10001 to 1561 points
2 - m: 1.9, n1: 0.51, n2=n3: 0.18
Pruned 10001 to 1328 points
3 - m: 1.9, n1: 1.80, n2=n3: 0.16
Pruned 10001 to 2328 points
4 - m: 1.9, n1: 0.21, n2=n3: 1.10
Pruned 10001 to 1981 points
5 - m: 1.9, n1: 0.63, n2=n3: 0.24
Pruned 10001 to 1664 points
6 - m: 1.9, n1: 0.45, n2=n3: 0.22
Pruned 10001 to 1290 points

Eyeballometrically, 60 PU pruning halves the number of plotted points, so the average data rate jumps from 9600 b/s to 19.2 kb/s. Zowie!

Most of the pruning occurs near the middle of the patterns, where the pen slows to a crawl. Out near the spiky rim, where the points are few & far between, there’s no pruning at all. Obviously, quantizing a generic plot to 1.5 mm would produce terrible results; in this situation, the SuperFormula produces smooth curves (apart from those spikes) that look just fine.

The Python source code as a GitHub Gist:

	# Adapted from Chiplotle plotter library:
	# http://cmc.music.columbia.edu/chiplotle/

	from chiplotle import *
	from math import *
	from datetime import *
	from time import *
	from types import *
	import random

	def supershape(width, height, m, n1, n2, n3,
	point_count=10 * 1000, percentage=1.0, a=1.0, b=1.0, travel=None):
	'''Supershape, generated using the superformula first proposed
	by Johan Gielis.

	– `points_count` is the total number of points to compute.
	– `travel` is the length of the outline drawn in radians.
	3.1416 * 2 is a complete cycle.
	modified to prune short plotter motions – Ed Nisley KE4ZNU – October 2016
	'''
	travel = travel or (10 * 2 * pi)

	# compute points…
	phis = [i * travel / point_count
	for i in range(1 + int(point_count * percentage))]
	points = [tools.mathtools.superformula(a, b, m, n1, n2, n3, x) for x in phis]

	# scale and prune short motions
	path = []
	path.append(Coordinate(width * points[0][0], height * points[0][1]))
	outi = 0
	xp, yp = points[outi][0], points[outi][1]
	for i in range(len(points))[1:]:
	x,y = width * points[i][0], height * points[i][1]
	dist = sqrt(pow(x – xp,2) + pow(y – yp,2))
	if dist > 60 :
	path.append(Coordinate(x, y))
	outi = i
	xp, yp = x, y

	path.append(Coordinate(width * points[-1][0], height * points[-1][1]))
	print " Pruned",len(points),"to",len(path),"points"

	return Path(path)


	# Run Superformula plots

	if __name__ == '__main__':

	override = False

	plt = instantiate_plotters()[0]
	# plt.write('IN;')

	if plt.margins.soft.width < 11000: # A=10365 B=16640
	maxplotx = (plt.margins.soft.width / 2) – 100
	maxploty = (plt.margins.soft.height / 2) – 150
	legendx = maxplotx – 2900
	legendy = -(maxploty – 750)
	tscale = 0.45
	numpens = 4
	# prime/10 = number of spikes
	m_values = [n / 10.0 for n in [11, 13, 17, 19, 23]]
	# ring-ness 0.1 to 2.0, higher is larger
	n1_values = [
	n / 100.0 for n in range(55, 75, 2) + range(80, 120, 5) + range(120, 200, 10)]
	else:
	maxplotx = plt.margins.soft.width / 2
	maxploty = plt.margins.soft.height / 2
	legendx = maxplotx – 3000
	legendy = -(maxploty – 900)
	tscale = 0.45
	numpens = 6
	m_values = [n / 10.0 for n in [11, 13, 17, 19, 23, 29, 31,
	37, 41, 43, 47, 53, 59]] # prime/10 = number of spikes
	# ring-ness 0.1 to 2.0, higher is larger
	n1_values = [
	n / 100.0 for n in range(15, 75, 2) + range(80, 120, 5) + range(120, 200, 10)]

	print " Max: ({},{})".format(maxplotx, maxploty)

	# spiky-ness 0.1 to 2.0, higher is spiky-er (mostly)
	n2_values = [
	n / 100.0 for n in range(10, 60, 2) + range(65, 100, 5) + range(110, 200, 10)]

	plt.write(chr(27) + '.H200:') # set hardware handshake block size
	plt.set_origin_center()
	# scale based on B size characters
	plt.write(hpgl.SI(tscale * 0.285, tscale * 0.375))
	# slow speed for those abrupt spikes
	plt.write(hpgl.VS(10))

	while True:

	# standard loadout has pen 1 = fine black
	plt.write(hpgl.PA([(legendx, legendy)]))
	pen = 1
	plt.select_pen(pen)
	plt.write(hpgl.PA([(legendx, legendy)]))
	plt.write(hpgl.LB("Started " + str(datetime.today())))

	if override:
	m = 4.1
	n1_list = [1.15, 0.90, 0.25, 0.59, 0.51, 0.23]
	n2_list = [0.70, 0.58, 0.32, 0.28, 0.56, 0.26]
	else:
	m = random.choice(m_values)
	n1_list = random.sample(n1_values, numpens)
	n2_list = random.sample(n2_values, numpens)

	pen = 1
	for n1, n2 in zip(n1_list, n2_list):
	n3 = n2
	print "{0} – m: {1:.1f}, n1: {2:.2f}, n2=n3: {3:.2f}".format(pen, m, n1, n2)
	plt.select_pen(pen)
	plt.write(hpgl.PA([(legendx, legendy – 100 * pen)]))
	plt.write(
	hpgl.LB("Pen {0}: m={1:.1f} n1={2:.2f} n2=n3={3:.2f}".format(pen, m, n1, n2)))
	e = supershape(maxplotx, maxploty, m, n1, n2, n3)
	plt.write(e)
	pen = pen + 1 if (pen % numpens) else 1

	pen = 1
	plt.select_pen(pen)
	plt.write(hpgl.PA([(legendx, legendy – 100 * (numpens + 1))]))
	plt.write(hpgl.LB("Ended " + str(datetime.today())))
	plt.write(hpgl.PA([(legendx, legendy – 100 * (numpens + 2))]))
	plt.write(hpgl.LB("More at https://softsolder.com/?s=7475a"))
	plt.select_pen(0)
	plt.write(hpgl.PA([(-maxplotx,maxploty)]))

	print "Waiting for plotter… ignore timeout errors!"
	sleep(40)
	while NoneType is type(plt.status):
	sleep(5)

	print "Load more paper, then …"
	print " … Press ENTER on the plotter to continue"
	plt.clear_digitizer()
	plt.digitize_point()

	plotstatus = plt.status
	while (NoneType is type(plotstatus)) or (0 == int(plotstatus) & 0x04):
	plotstatus = plt.status

	print "Digitized: " + str(plt.digitized_point)

view raw PlotterShapes.py hosted with ❤ by GitHub

2016-10-20

ATM Error Message

Saw this after fat-fingering my PIN at a drive-up ATM:

ATM Screen Display Error Message

That’s off-putting, isn’t it?

2016-10-19
Sharing the Road on Raymond Avenue: Impatience

We recently had one of those rare “Get the fuck off the road” incidents on Raymond. To set the stage, we’re on our way for groceries and I’m towing the trailer.

The rear view shows the second car behind us veering far to the right side of the lane, trying to see around the car ahead of him, with much blowing of horn:

Raymond Ave – Impatience – 2016-09-27 – 1

The big GMC had been following us at a reasonable distance from the Juliet roundabout as we trundled along Raymond at about 12 mph, riding out of the Door Strike Zone for well and good reason.

The GMC passed us at the end of the median, which let the impatient driver zoom up next to us. You can’t hear the horn that will blow as he pulls up next to me:

Raymond Ave – Impatience – 2016-09-27 – 2

Our usual route takes us into Davis St, so Mary’s already leaning into the right turn. I think he intended to go straight on Raymond for at least another block to the arterial, but he made an abrupt right turn into Davis St directly in front of me:

Raymond Ave – Impatience – 2016-09-27 – 3

Perhaps that’s to Teach Us A Lesson after all the horn-blowing?

I always ride behind Mary and slightly to her left, so that if / when bad shit goes down, I can bring it down on me, rather than her. In this case, she was safely beyond what was about to happen:

Raymond Ave – Impatience – 2016-09-27 – 4

The wide-angle lens is deceiving, as I’m less than three feet from the car and closing rapidly; I’m obviously not turning as sharply as he expected and I’m not slowing to avoid a collision. There’s a parked car just ahead of Mary, to her right, and her path is as far to the right as it can get.

He apparently realized that Teaching Me A Lesson would produce a nasty scuff on the side of his shiny black car and, perhaps having spotted the helmet camera, a nasty loss in the ensuing insurance squabble. He also wasn’t willing to swing wide, head-on into the oncoming lane of Davis, so he stopped dead in the intersection:

Raymond Ave – Impatience – 2016-09-27 – 5

That’s fine with me.

I continued wide past the parked car on Davis. He accelerated hard, decided, once again, not to ram me from behind, turned abruptly left into the parking lot, and proceeded to the eastbound arterial:

Raymond Ave – Impatience – 2016-09-27 – 6

I’m stopped in that picture to aim the helmet camera backwards over my left shoulder. The car behind the white one is parked near the intersection, just to my right in the previous picture.

As nearly as I could make out, he shouted, in addition to the usual obscenities, “Roads are for automobiles!”, a surprisingly articulate word under the circumstances. Evidently, he hadn’t noticed NYSDOT’s “Share the Road” signage helpfully posted on the far end of Raymond.

Elapsed time from the Juliet roundabout to the parking lot: 45 seconds.

Maybe he had a cake in the oven?

2016-10-18

Reticle Guide for Ruler Quilting

I made the pencil guides to help Mary design ruler quilting patterns, but sometimes she must line up the ruler with a feature on an existing pattern. To that end, we now have a reticle guide:

Ruler Adapters - pencil guide and reticle — Ruler Adapters – pencil guide and reticle

The general idea is that it’s easier to see the pattern on paper through the crosshair than through a small hole. You put the button over a feature, align the reticle, put the ruler against the button, replace it with pencil guide, and away you go.

The solid model looks much more lively than you’d expect:

Ruler Adapter - reticle - Slic3r preview — Ruler Adapter – reticle – Slic3r preview

Printing up a pair of each button produces the same surface finish as before; life is good!

The OpenSCAD source code as a GitHub Gist:

	// Quilting Ruler Adapters
	// Ed Nisley KE4ZNU October 2016

	//- Extrusion parameters must match reality!

	ThreadThick = 0.25;
	ThreadWidth = 0.40;

	HoleWindage = 0.2;

	Protrusion = 0.1; // make holes end cleanly

	inch = 25.4;

	function IntegerMultiple(Size,Unit) = Unit * ceil(Size / Unit);

	//———-
	// Dimensions

	ID = 0;
	OD = 1;
	LENGTH = 2;

	Offset = 0.25 * inch;

	Template = [2.0,2*Offset,3.0];

	NumSides = 16*4;
	HoleSides = 8;

	//———————-
	// Useful routines

	module PolyCyl(Dia,Height,ForceSides=0) { // based on nophead's polyholes
	Sides = (ForceSides != 0) ? ForceSides : (ceil(Dia) + 2);
	FixDia = Dia / cos(180/Sides);
	cylinder(d=(FixDia + HoleWindage),h=Height,$fn=Sides);
	}


	//———-
	// Build them

	translate([-Template[OD],0,0])
	difference() {
	cylinder(d=Template[OD],h=Template[LENGTH],$fn=NumSides);
	translate([0,0,-Template[LENGTH]])
	PolyCyl(Template[ID],3*Template[LENGTH],HoleSides);
	translate([0,0,-Protrusion])
	cylinder(d1=2*Template[ID],d2=Template[ID],h=Template[LENGTH]/3 + Protrusion,$fn=HoleSides);
	translate([0,0,Template[LENGTH] + Protrusion])
	mirror([0,0,1])
	cylinder(d1=2*Template[ID],d2=Template[ID],h=Template[LENGTH]/3 + Protrusion,$fn=HoleSides);
	}

	translate([Template[OD],0,0])
	difference() {
	cylinder(d=Template[OD],h=Template[LENGTH],$fn=NumSides);
	for (a=[45,135])
	rotate(a)
	cube([0.70Template[OD],0.15Template[OD],3*Template[LENGTH]],center=true);
	}

view raw Ruler Adapters.scad hosted with ❤ by GitHub

2016-10-17

Grasshopper on Broccoli

This critter has been ravaging the broccoli plants in Mary’s Vassar Farms plot:

Grasshopper – Broccoli at Vassar Farms garden

Nothing to do but eat, excrete, and procreate in the warm sun:

Grasshopper – Broccoli at Vassar Farms garden – overview

Life is good!

She can’t bring herself to mash it, as she does with the myriad other critters having no redeeming virtues. Grasshoppers, it seems, have good PR agents.

2016-10-16

Author: Ed

Satellite Dish Mounting Angle in Norway

Raspberry Pi Streaming Radio Player: Improved Pipe Handling

HP 7475A Plotter: Coordinate Pruning

ATM Error Message

Sharing the Road on Raymond Avenue: Impatience

Reticle Guide for Ruler Quilting

Grasshopper on Broccoli