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Commit 3dad18f0 authored by Eric Kooistra's avatar Eric Kooistra
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Detailed design: Transient Buffer function (LIFT) Detailed design: Transient Buffer function (LIFT)
References:
[1] https://plm.astron.nl/polarion/#/project/LOFAR2System/workitem?id=LOFAR2-12060 Transient buffer data
1) DDR4 memory per receiver input 1) DDR4 memory per receiver input
...@@ -12,8 +14,14 @@ The receiver input data rate is f_adc = 200 MHz and sample width is W_adc = 14 b ...@@ -12,8 +14,14 @@ The receiver input data rate is f_adc = 200 MHz and sample width is W_adc = 14 b
Assume the samples are stored in 16 b (= 2 bytes), this creates 16/14 = 14 % storage overhead Assume the samples are stored in 16 b (= 2 bytes), this creates 16/14 = 14 % storage overhead
Assume 4 % storage overhead for packet header information Assume 4 % storage overhead for packet header information
==> Per recveiver input T_tbuf = 1.33 GByte / (2 byte/sample) / 1.04 / f_adc = 3.2 sec maximum storage time. ==> Per recveiver input T_tbuf = 1.33 GByte / (2 byte/sample) / 1.04 / f_adc = 3.2 sec maximum storage time.
==> Per recveiver input T_tbuf = 1.33 GByte = 10.6 Gbit, so at full 10GbE rate it takes about 1 s to read all samples from 1 receiver input
==> 192 * 1.33 = 256 GByte / LB for T_tbuf = 3.2 s ==> 192 * 1.33 = 256 GByte / LB for T_tbuf = 3.2 s
In [1] time series data en pulse data, wat is pulse data ?
Hoe streng is de 3.33 s, mag 3.2 s ook ? Hoe streng is de 3.33 s, mag 3.2 s ook ?
Moeten we nog grotere 16 GByte modules gaan aanschaffen en te testen met unb2c, zodat we 2x zoveel storage tijd hebben ? Gebruik een 16 GByte module per FPGA, zodat uitbreiding naar 6.66 s mopgelijkl is door beide slots the gebruiken
Uitlezen per receiver input, zodat uitlezen van een deel vd receiver inputs mogelijk is (bijv 12 vd 192 in [1])
Defineer TB functie per receiver input:
. zodat de TB functie makkelijk uitbreidbaar is naar meer inputs en naar meer DDR4 modules.
. data capture en uitlezen van een receiver input onafhankelijk kan van de andere receiver inputs
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