To: File

From: Jon Hagen

Date: April 10, 2003, 4-16-03 , 5-21-03

Subject: Alfa backend requirements - summarized by Avinash Deshpande in a conversation following an Alfa meeting today:

Bandwidth	Polizar-

izations	Chann els	Input

Levels	Output

Levels	Dump

Time	Misc.	WAAP

Performance
P-Alfa

(pulsar)

Cordes	300 MHz	PA+PB

or

PA & PB	1000

(300 kHz res.)	8 bits

min	4 bits max

(flexible)

(includes mode in which polarizations are

added)	64 usec

for 7000x 1/2B

= 55B/usec=

55MB/s

or 8B/usec =

8MB/s per feed	output after

long-term mean

removed in SW	100MHz BW, 1.6bits

459 kHz 3dB res @64 us (392 lags)w/ cos^2 smoothing
E-Alfa

(extra-galactic)

Giovaneli, Karen	200 MHz min	8192

(25 kHz res.)	8 bits min

(12 desired)	16 bits min

@ 1 sec dumps

(polarizations kept seperate)	1 sec

(or less for rfi)

for 14 x 8192 x 2B = 0.23MB/sec	flexible blanking

in hardware	100MHz,

48kHz (3lev)

97kHz(9lev)
G-Alfa HI(galactic)

Goldsmith,Snez,

Loris,Martha

Heiles

Lochman

Berkeley Galfa Machine, narrow

band section

1415-1425 MHz

100MHz Input Band, then

selectable

7 MHz channel

PA & PB	1 kHz res. min

=10k chann els

(20k desire d)

7MHz
/8192 =0.8

kHz

10 desired

(few ok if little rfi)

8 bits	10 bits

32 bits	1 sec

1 sec	blanking not

needed*

none	(Software

spectrum analyhzer)
G-Alfa RRL

Terzian

Mayra Lebron

One 6MHz band

+ eleven 3MHz

bands (all fixed)	PA+PB?	0.5kHz

1kHz min

(~40k channe ls)	8 bits min	10 bits	<1 sec	blanking not

needed*	SED
G-Alfa

continuum

(like P-Alfa

but w/fullstokes

Chris Salter

Berkeley Galfa Machine, wide

band ssection

300 MHz

100 MHz	full

Stokes

No Stokes	1k

256	8 bits min

8 bits	16 bits

32 bits	.1 sec

1 second	blanking

not needed*

no blanking
*rfi excised in software