fix: hw4 knit

hw4.Rmd

@@ -1,4 +1,15 @@
-# HW 4
+---
+title: "HW4"
+subtitle: "Software Defined Radio"
+output: pdf_document
+date: "`r Sys.Date()`"
+---
+
+```{r setup, include=FALSE}
+knitr::opts_chunk$set(echo = TRUE)
+```
+
+# Assignment
 Write an R script to calculate the output of the Klobuchar model.
 Provide a GUI means for entering input data, and the name and the
 path to navigation message file with coefficients of the Klobuchar
@@ -9,14 +20,18 @@ signal during 24 hours of a given day, in 1-minute increments, with
 the given coefficients of the ionospheric model. Verify the correctness
 of the algorithm implementation with a given numerical example. After
 that, conduct a 24-hour simulation of the GPS ionospheric delay in 1-
-minute increments for the position φu = 45.33709°, λu = 14.42496°, E
-= 90°, A = 180°. Store the estimated 24-hour simulation data set in a
+minute increments for the position $\varphi_u$ = 45.33709°, $\lambda_u$ = 14.42496°, $E$
+= 90°, $A$ = 180°. Store the estimated 24-hour simulation data set in a
 dedicated file on the local disc.
 
 The problem description, method, R script and implementation results
 should be presented in a single HTML document, which should be
 sent to the subject teacher's e-mail by May 21, 2026 at 23:59 CEST.
 
+```{r select-file}
+library(rstudioapi)
+rinex_file <- rstudioapi::selectFile()
+```
 
 ```{r read-file}
 # Function to extract Klobuchar parameters from a RINEX navigation file
@@ -49,8 +64,43 @@ extract_klobuchar_parameters <- function(rinex_file) {
   )
 }
 
-rinex_file <- "brdc0930.26n"
 klobuchar_params <- extract_klobuchar_parameters(rinex_file)
 
 print(klobuchar_params)
 ```
+
+```{r select-date}
+# TODO
+selected_date <- as.Date("2000-1-1")
+```
+
+## Klobuchar calculation
+1. Calculate earth-centered angle
+What are R_E and h?
+$$ \psi = \pi/2 - E - \arcsin(\frac{R_E}{R_E + h} \cos(E))  $$
+
+
+2. Compute the latitude of the IPP (ionospheric pierce point)
+$$ \phi_I = \arcsin( sin \varphi_u \cos \psi + \cos\varphi_u \sin\psi \cos A )$$
+3. Compute the longitude of the IPP
+$$ \lambda_I= \lambda_u + \frac{\psi \sin A}{\cos \phi_I}$$
+4. Find the geomagnetic latitude of the IPP
+What is phi_P?
+$$ \phi_m = \arcsin(\sin\phi_I \sin\phi_P + \cos\phi_I \cos\phi_P \cos(\lambda_I - \lambda_P)) $$
+5. Find the local time at the IPP
+$$ t = 43200 \lambda_I / \pi + t_{GPS} $$
+$\lambda_I$ in radians, $t$ in seconds.
+where $0 \leq t \leq 86 400$. Therefore:
+If $t \geq 86 400$, subtract $86 400$. If $t < 0$, add $86 400$.
+
+6. Compute the amplitude of ionospheric delay
+$$ A_I = \sum_{n=0}^{3} \alpha_n(\phi_m/\pi)^n $$
+If $A_I < 0$, then $A_I =0$.
+```{r simulate}
+# input constants
+lat = 45.33709 # phi
+lon = 14.42496 # lambda
+E = 90
+A = 180
+
+```

notes.md

@@ -1,4 +1,7 @@
 # SDR
+## Packages
+signal
+gsignal
 ## Software
 https://gnss-sdr.org/docs/overview/
 https://gage.upc.edu/en/learning-materials/software-tools/glab-tool-suite

renv.lock

@@ -828,6 +828,34 @@
       "Maintainer": "Yihui Xie <xie@yihui.name>",
       "Repository": "CRAN"
     },
+    "rstudioapi": {
+      "Package": "rstudioapi",
+      "Version": "0.18.0",
+      "Source": "Repository",
+      "Title": "Safely Access the RStudio API",
+      "Description": "Access the RStudio API (if available) and provide informative error messages when it's not.",
+      "Authors@R": "c( person(\"Kevin\", \"Ushey\", role = c(\"aut\", \"cre\"), email = \"kevin@rstudio.com\"), person(\"JJ\", \"Allaire\", role = c(\"aut\"), email = \"jj@posit.co\"), person(\"Hadley\", \"Wickham\", role = c(\"aut\"), email = \"hadley@posit.co\"), person(\"Gary\", \"Ritchie\", role = c(\"aut\"), email = \"gary@posit.co\"), person(family = \"RStudio\", role = \"cph\") )",
+      "Maintainer": "Kevin Ushey <kevin@rstudio.com>",
+      "License": "MIT + file LICENSE",
+      "URL": "https://rstudio.github.io/rstudioapi/, https://github.com/rstudio/rstudioapi",
+      "BugReports": "https://github.com/rstudio/rstudioapi/issues",
+      "RoxygenNote": "7.3.3",
+      "Suggests": [
+        "testthat",
+        "knitr",
+        "rmarkdown",
+        "clipr",
+        "covr",
+        "curl",
+        "jsonlite",
+        "withr"
+      ],
+      "VignetteBuilder": "knitr",
+      "Encoding": "UTF-8",
+      "NeedsCompilation": "no",
+      "Author": "Kevin Ushey [aut, cre], JJ Allaire [aut], Hadley Wickham [aut], Gary Ritchie [aut], RStudio [cph]",
+      "Repository": "CRAN"
+    },
     "sass": {
       "Package": "sass",
       "Version": "0.4.10",