# float solution for LAMBDA

Discussion in 'GPS Technical Discussion' started by venky_vish, Oct 3, 2014.

1. ### venky_vish

Joined:
Oct 3, 2014
Messages:
1
0
Hello Everyone

I am researching on LAMBDA implementation to calculate the integer ambiguity.
y = Aa + Bb
y is the observed double difference for each epoch .
A is the design matrix with normalized LOS vector
B is a diagonal matrix of the wavelength .

As a first step I calculate the float solution and I need help with this.
The model used are popular ones referred by P.J. de Jonge ,CCCJM Tiberius and Teunissen

This is a sample y vector DD of code and phase
1.e+5*
0.0004
-0.0009
-0.0007
-0.0000
-1.9138
-1.0779
0.0778
0.2645

Question :
1. Can I just take y * y' (i,e y * y transpose ) to calculate the variance Qy?

2.Is there a sample code with numerical examples including actual GPS data that calculate the float ambiguities and variance matrix?

I tried but covariance matrix Qa had a huge value order of e^10!

thanks

venky_vish, Oct 3, 2014

2. ### Jhabindra Khanal

Joined:
Mar 9, 2015
Messages:
2
0
Hello sir,
venky_vish,
I want to know that how did u use satellites to form single and double difference. I saw in your question there is a DD phase vector. could you provide me the line of mat-lab code for doing double difference . ?? and how to form numerically double difference to find float solution??