Signal processing:

Creating harmonics (how strong the various freq terms are)
Harmonics created when clipping a sine wave.
Side band harmonics do not always move farther out than at the fundamental.
Problems using a 90 deg hybrid to convert linear to circular (lbw example)
properities of a gaussian
properteis of sin(x)/x

Computing Trcvr.
Telescope gain
Yfactor, measuring Tscattered for horn on antenna.
pulsarNotes
Beamwidth, near/far field transition
satellite orbits: velocity,angular velocity, period vs radius
sun,moon separation during 21aug17 eclipse

Idl use of color

List of cpu compute servers at AO.
Disc locations by cpu
Backing up of monitor data.
bitfield storage format. converting big endian to little endian.
Ao Network Info

• side band harmonics do not always move farther out than at the fundamental. (top)

Suppose you have a tone of  Amplitude A and frequency w and a side band of amplitude B  and frequency (w+delta)
then:

If B << A then the AB term will be much larger than the BB term so the +delta signal will be stronger than the 2*delta.

• Gaussian: (top)

A gaussian centered at x=0 can be  defined as:
y1= 1./sqrt(2*pi)*e^{-.5*(x/sig)^2)}   integral normalized to unity
y2=                          e^{-(x/sig)^2)}    y2(x=0)=1.     y2(x=1)=e^-1= .367879
Properties are:
 

property	y1	y2
maxvalue y(0)	y1(0)=.398942	y2(0)=1.
y(sig)	y1(sig)=.2419707	y2(sig)=.367879
integral -inf to inf	1.	sqrt(pi)=1.77245
FWHM=m*sig (see  1*) sig=n*FWHM	m=2.35482 n=.424661	m=1.66511 n=.60056118

 
1*
y1=A0/2=A0*e^{(-.5*x/sig)^2)}
sqrt(2*ln(2))*sig=x(hwhm)
FWHM=2*x =2*sqrt(2*ln(2))
y2=1/2=e^{(-(x/sig)^2)}
sqrt(ln(2))*sig=x(hwhm)
FWHM=2*x= 2*sqrt(ln(2))*sig

• sin(x)/x  (top)

y=sin(x)/x . If x is defined in units of the first null, then use sin(pi*x)/(pi*x)
 

property
maxvalue : y(0)	1.
minvalue  :y	y=-.2172336, x=4.4934100..
zero crossings	pi*n n=1..
peaks,min	when x=tan(x) (more info) for large x :close to x=(2n+1)pi/2
x when y=.5	x=1.8954950
integral between 1st  nulls (-pi,pi)	integral: 9.8696191

---

rms voltages needed for 2,3,4, and 5 bit sampling.  (top)

---

Compute Trcvr.  (top)

• T1 and T2 be the temperatures of these loads.
• gamma is the voltage reflection at the input to the horn. let G2=(1-gamma^2). It will be the fraction of the input power that gets into the device
• alpha is the loss in the omt, Tomt is the temperature of the omt. (1-alpha) of the entering temp will be passed through. (1-alpha)*Tomt will be contributed by the omt temp.
• Tamp is the amplifier temperature. Trcv is normally Tamp +  alpha*Tomt.

Y=Pwr2/Pwr1 
y=(Tamp + alpha*Tomt + (1-gamma^2)(1-alfa)T2)/(Tamp + alpha*Tomt + (1-gamma^2)(1-alpha)T1)

Tamp(1-Y)=Y(alpha*Tomt + (1-alpha)(1-gamma^2)*T1) - (alpha*Tomt + (1-alpha)(1-gamma^2)T2)

Tamp= (1-alpha)(1-gamma^2)*(T2-Y*T1)/(Y-1) - alpha*Tomt

---

Telescope gain  (top)

• Ae= effective area (aperture). (PowerExtracted/IncidentFlux)
• nA=aperture efficiency ( Ae/Ag) Ag=geometric aperture)
• D=Gmax=4piAe/(lamda^2) or
• Ae*bmSa = lamda^2 (bmSa=beam solid angle)
  

• 1 K/Jy is 2760 m^2
• for a uniformilly illuminated circular appeture: hpbw=1.02*lambda/D
• if plane wave with energy power density S hit telescope. The telescope extracts Pe energy then the effective area of the telescope is Ae=Pe/S
• The appeture efficiency is Na=Ae/Ag  where Ag is the geometric area.
• Gmax=4*pi*Ae/lambda^2
• Ae*OmegaA=lambda^2 where OmegaA is the beam solid angle (integrated over 4pi steradian).
• OmegaMb is the main beam solid angle. Defined to be the solid angle that has the same area as the mainbeam down to the first nulls.

Pulsars

• dm smearing across a band
• tmSmMillisecs= (202/cfrMhz)^3 * dm *BwMhz
  
• optimum channel width for incoherent processing
• 1/channelwidth  = dmsmearing across the channel..
  
• or
• 1./(bw/nchan) = dmSmearingbw/nchan
  
• nchan/dmSmearingBw = bw/nchan
  
• nchan= sqrt(bw*dmSmearingBw)  optimum.. or
  
• nchan=sqrt(bwMHz^2 * (202/cfrMhz)^3 * dm * 1e3)
  

Satellite orbits

    The plots show satellite orbital velocities, angular velocity, and orbital periods vs radius (.ps) (.pdf)

• Page 1: orbits vs radius from center of earth
• top: velocity km/sec
• 2nd: velocity km/hour
• 3rd: obital angular velocity
• 4th orbital period in hours
• Page 2: orbits versus distance above the earth
  
• Page 3: blowup showing 0.. 1000 km above the earth's surface.
• The dashed red lines shows the geostationary orbit.
• Page 4: How long a satellite is above the observers horizon (assuming sea level, min elevation=0)
• Page 5: How fast does a telescope need to move to track satellites at various heights..
• red lines show the 12meter limit (50 km?) and the 305 m limit (6000 km).
• The lines are the max velocities.. you probably can't track continually at this speed (you always need a little extra if you ever need to catch up..).
  

170821 sun moon separation as see from AO

    I plotted up the sun,moon separation for the 21aug17 eclipse (as seen from arecibo observatory).
I used the jpl horizons ephemerides to compute the separation.

    the plot  shows the sun moon separation (.ps) (.pdf)

• the moon, sun edges will start to intersect at 14:18 ast
• the minimum distance (maximum for eclipse) will occur at 15:34:00.3 ast
• the minimum separation (of their centers) will be .099 degrees (about 6 arc minutes).
  
• the moon , sun will finish their overlap at 16:40

svn

repository structure

• How directories are used:
• trunk
• main developement goes on here
• branches
• Different versions stores with possible updates needed to fix a version
• tags:
• snapshots of a particular version. It is frozen. Might be easier to role back

• /share/megs/phil/svnrepos  : the repository
  
• Cima
• branches
• mocksp
• Software
  
• tags
• V3.0.10    (normal)
  
• Software
  
• V3.1.03     (smart)
  
• Software
  
• trunk
• Software
  
• idl -  holds  phil's idl code
  
• branches
• tags
• trunk
• idl directories under /pkg/rsi/local/libao/phil
  
• pdev - the datataking system for pdev. excludes jeff's code
  
• branches
  
• tags
• rev-1026/  before parallactic angle changes 16feb09
  
• rev-879/    before psrfits changes.
  
• trunk
• Readme
• aosoft/
• linux.sh
• linuxfiles/
• pdev/
  
• vw - vxWorks datataking code from /home/phil/vw/
  
• branches
• tags
• trunk
• directory under /home/phil/vw/
• vwTcl - tcl procedures for vxWorks. from /home/online/vw/Tcl
• branches
• tags
• trunk
• code from /home/online/vw/Tcl
  

svn commands

• list contents of repository:
• svn list file:///share/megs/phil/svnrepos
• copy a new set of files into the repository
• svn import
  

svn notes CIMA

• Locations:
• file:///share/megs/phil/svnrepos/Cima   .. repository
• Online cima versions:
• /home/cima/Software/XX   XX= Mocksp, Svnwork
• Working directories
• /home/cima/svn/Cima/XX     XX = svnwork,mocksp, etc..

• svn list file:///share/megs/phil/svnrepos/Cima
• checkout to a working directory
  
• cd /home/cima/svn/Cima/ ; mkdir mocksp
  
• svn -r revision checkout file:///share/megs/phil/svnrepos/Cima/trunk  /home/cima/svn/Cima/mocksp
  
• Make Svnwork a new cima version release (eg. Mocksp)
• make sure svn repository uptodate for svn/Cima/svnwork svn -u status
• record svn version number
• cd /home/cima/svn/Cima/svnwork
• make install
• moves most recent updates to Svnwork
• does a cmake install aon Frontend,Exectuive, tcl_utilities, then copies the version files back to Cima/svnwork/Software.
  
• add /home/cima/bin to front of path variable (to find cmake)
  
• Copy online version Svnwork to new version
• cima_copy Svnwork Mocksp
• answer Questions: mocksp  3.2.00
• Make a branch for a new version in the svn repository.
  
• svn copy file:///share/megs/phil/svnrepos/Cima/trunk file:///share/megs/phil/svnrepos/cima/branches/mocksp -m "creating  mocksp branch from trunk revision (revision number from status above)"
• checkout the mocksp version
  
• cd /home/cima/svn/
• svn checkout file:///share/megs/phil/svnrepos/Cima/trunk/Software mocksp
  

SVN notes pdev

home_~phil